First of all, I'm sorry for sending this message to the group, but I know no other way to contact the development team. And as always, I apologize for eventual attempts to murder the English language.

The attached model represents a sewer pumping system. Units are LPS, so piping diameters are in millimeters and tank's diameters are in meters. As it is easy to notice, pump EEE1 fills in the tank (suction pit - PS-EEE2) for EEE2. EEE2 then pumps the sewer flow to EEE3, that operates with a standing pipe so automation can read the level to speed up/down pump EEE3. EEE3 standing pipe's diameter is 1 meter and works with free surface, exactly like a tank.

As this standing pipe fills in too fast, time steps are set to 1 minute. Simulation runs ok, and the bug manifests between times 0:23 and 0:28 pump EEE1 is ON. So, tank PS-EEE2 should be filling in quickly, around 0.5m per minute. But no change is seen in the tank's level. It repeats a lot. The GUI does not registers the level change, and I'm not sure if the simulator does. The same happens if the time steps are set as low as they can go, I think it is the decimal value 0.0028, and becomes easier to see in the GUI.

As soon as I have some spare time I'll estimate this filling in times to check if this is in the GUI only or in the simulator as well.

Note: The listserv blocked both my .net and .inp attachments. So I've pasted the entire inp file below. I hope it works. If it doesn't, I can send the files if requested.

[TITLE]

[JUNCTIONS]
;ID               Elev         Demand       Pattern
Q1               0           -41.4                        ;
2               960         0                            ;
3               960         0                            ;
4               960         0                            ;
5               0           0                            ;
Q2               0           -17.37                       ;
7               961.44       0                            ;
8               96.44       0                            ;
9               961.44       0                            ;
10               0           0                            ;
11               1008.38     0                            ;
12               1008.38     0                            ;
14               1008.38     0                            ;
1               993.4       0                            ;
6               993.4       0                            ;

[RESERVOIRS]
;ID               Head         Pattern
13               1055.6                       ;

[TANKS]
;ID               Elevation   InitLevel   MinLevel     MaxLevel     Diameter
MinVol       VolCurve
PS-EEE1         950.114     1.85         0           3           3.09905
0                            ;
PS-EEE2         956.15       2.05         0.55         5           3.426
0                            ;
SP               1008.38     .5           0.19         11.5         1
0                            ;

[PIPES]
;ID               Node1           Node2           Length
Diameter     Roughness
MinorLoss   Status
1               PS-EEE1         2               6.7         250         138
7           Open   ;
3               3               4               1.5         250         138
5           Open   ;
4               4               5               304         250         138
3           Open   ;
5               5               1               766         253.2       140
3           Open   ;
7               PS-EEE2         7               6.7         250         138
7           Open   ;
8               8               9               1.5         250         138
5           Open   ;
9               9               10               485         250         138
3           Open   ;
10               10               11               340         246.8       140
3           Open   ;
11               11               12               10           250
138         2           Open   ;
12               12               SP               5           250         138
2           Open   ;
13               14               13               337         250         138
3           Open   ;
14               Q1               PS-EEE1         1000         500         138
0           Open   ;
15               Q2               PS-EEE2         1000         500         138
0           Open   ;
6               6               PS-EEE2         1000         500         138
0           Open   ;

[PUMPS]
;ID               Node1           Node2           Parameters
EEE1             2               3               HEAD EEE1HIA ;
EEE2             7               8               HEAD EEE2HIA ;
EEE3             12               14               HEAD EEE3 SPEED 0.9648 ;

[VALVES]
;ID               Node1           Node2           Diameter     Type Setting
MinorLoss
2               1               6               12           PSV 0.1
0           ;

[TAGS]

[DEMANDS]
;Junction         Demand       Pattern         Category

[STATUS]
;ID               Status/Setting
EEE3             0.9648

[PATTERNS]
;ID               Multipliers
;
1               0.5         0.606939233 0.712048706 0.813529966 0.909646643
0.998754151
1               1.079327838 1.149989064 1.209528798 1.256928297 1.291376543
1.312284118
1               1.319293285 1.312284118 1.291376543 1.256928297 1.209528798
1.149989064
1               1.079327838 0.998754151 0.909646643 0.813529966 0.712048706
0.606939233
1               0.5

[CURVES]
;ID               X-Value     Y-Value
;PUMP:
1               1           1
1               2           0.5
;PUMP:
EEE1HIA         0.880787     70.8003
EEE1HIA         6.16831     68.8759
EEE1HIA         11.4608     66.9659
EEE1HIA         16.7836     65.0961
EEE1HIA         22.1484     63.2807
EEE1HIA         27.549       61.5194
EEE1HIA         32.9704     59.8069
EEE1HIA         38.3884     58.1246
EEE1HIA         43.778       56.4579
EEE1HIA         49.1228     54.7916
EEE1HIA         54.4145     53.1194
EEE1HIA         59.656       51.4366
EEE1HIA         64.8651     49.7546
EEE1HIA         70.0613     48.0853
EEE1HIA         75.2652     46.4412
EEE1HIA         80.496       44.8398
EEE1HIA         85.7618     43.2948
EEE1HIA         91.0515     41.8089
EEE1HIA         96.3409     40.3739
EEE1HIA         101.574     38.9808
EEE1HIA         106.685     37.5484
EEE1HIA         111.717     36.1189
EEE1HIA         116.61       34.4825
EEE1HIA         121.658     32.9046
EEE1HIA         126.608     31.259
EEE1HIA         131.51       29.5426
EEE1HIA         136.529     27.8382
EEE1HIA         141.607     26.1661
EEE1HIA         146.683     24.5284
EEE1HIA         151.701     22.81
;EFFICIENCY:
EEE1ef           0.880787     1.6955
EEE1ef           6.16831     11.0918
EEE1ef           11.4608     19.2967
EEE1ef           16.7836     26.5183
EEE1ef           22.1484     32.839
EEE1ef           27.549       38.3254
EEE1ef           32.9704     43.0468
EEE1ef           38.3884     47.0644
EEE1ef           43.778       50.4338
EEE1ef           49.1228     53.2463
EEE1ef           54.4145     55.587
EEE1ef           59.656       57.4685
EEE1ef           64.8651     59.0962
EEE1ef           70.0613     60.4973
EEE1ef           75.2652     61.575
EEE1ef           80.496       62.4675
EEE1ef           85.7618     63.2223
EEE1ef           91.0515     63.8289
EEE1ef           96.3409     64.2372
EEE1ef           101.574     64.3636
EEE1ef           106.685     64.1316
EEE1ef           111.717     63.6803
EEE1ef           116.61       62.7393
EEE1ef           121.658     61.7278
EEE1ef           126.608     60.4367
EEE1ef           131.51       58.8876
EEE1ef           136.529     57.2622
EEE1ef           141.607     55.5525
EEE1ef           146.683     53.7328
EEE1ef           151.701     51.5199
;PUMP:
EEE2HIA         0           88.0062
EEE2HIA         6.57373     86.4724
EEE2HIA         13.1295     84.9208
EEE2HIA         19.689       83.387
EEE2HIA         26.2704     81.9007
EEE2HIA         32.8715     80.4638
EEE2HIA         39.4771     79.0642
EEE2HIA         46.0626     77.6813
EEE2HIA         52.6115     76.2912
EEE2HIA         59.1167     74.888
EEE2HIA         65.581       73.4719
EEE2HIA         72.0182     72.0513
EEE2HIA         78.4449     70.6423
EEE2HIA         84.8692     69.2587
EEE2HIA         91.2882     67.9041
EEE2HIA         97.688       66.581
EEE2HIA         104.033     65.2724
EEE2HIA         110.279     63.9547
EEE2HIA         116.39       62.5934
EEE2HIA         122.34       61.1546
EEE2HIA         128.131     59.6054
EEE2HIA         133.797     57.9216
EEE2HIA         139.382     56.1026
EEE2HIA         144.929     54.1642
EEE2HIA         150.47       52.1503
EEE2HIA         156.025     50.1063
EEE2HIA         161.606     48.0831
EEE2HIA         167.198     46.1022
EEE2HIA         172.764     44.1502
EEE2HIA         178.306     42.1842
;PUMP:
EEE2ef           0           0
EEE2ef           6.57373     9.02106
EEE2ef           13.1295     16.9553
EEE2ef           19.689       23.9219
EEE2ef           26.2704     30.0436
EEE2ef           32.8715     35.4116
EEE2ef           39.4771     40.1054
EEE2ef           46.0626     44.1909
EEE2ef           52.6115     47.7011
EEE2ef           59.1167     50.735
EEE2ef           65.581       53.3561
EEE2ef           72.0182     55.6232
EEE2ef           78.4449     57.5873
EEE2ef           84.8692     59.2663
EEE2ef           91.2882     60.665
EEE2ef           97.688       61.7962
EEE2ef           104.033     62.6292
EEE2ef           110.279     63.1095
EEE2ef           116.39       63.2222
EEE2ef           122.34       62.9599
EEE2ef           128.131     62.3119
EEE2ef           133.797     61.3128
EEE2ef           139.382     60.0338
EEE2ef           144.929     58.5351
EEE2ef           150.47       56.8882
EEE2ef           156.025     55.1568
EEE2ef           161.606     53.3988
EEE2ef           167.198     51.6328
EEE2ef           172.764     49.835
EEE2ef           178.306     47.9635
;PUMP: rotor 370mm
EEE3             0.00         71.68
EEE3             33.21       64.82
EEE3             49.81       61.48
EEE3             66.42       57.57
EEE3             74.72       55.41
EEE3             83.02       53.13
EEE3             99.62       47.88
EEE3             116.23       41.10
;EFFICIENCY:
EEE3ef           0.00         0.00
EEE3ef           45.15       51.07
EEE3ef           67.73       58.78
EEE3ef           90.30       61.89
EEE3ef           101.59       62.13
EEE3ef           112.88       61.68
EEE3ef           135.45       59.03
EEE3ef           158.03       55.60

[CONTROLS]

[RULES]

RULE EEE1START
IF NODE PS-EEE1 PRESSURE > 1.85
THEN PUMP EEE1 STATUS IS OPEN
PRIORITY 1

RULE EEE1END
IF NODE PS-EEE1 PRESSURE < 0.5
THEN PUMP EEE1 STATUS IS CLOSED
PRIORITY 1

RULE EEE2START
IF NODE PS-EEE2 PRESSURE > 2.05
THEN PUMP EEE2 STATUS IS OPEN
PRIORITY 1

RULE EEE2END
IF NODE PS-EEE2 PRESSURE < 0.55
THEN PUMP EEE2 STATUS IS CLOSED
PRIORITY 1

RULE EEE3START
IF NODE SP PRESSURE > 2.75
AND NODE SP PRESSURE < 3.99
THEN PUMP EEE3 STATUS IS OPEN
AND PUMP EEE3 SETTING IS 0.9648
PRIORITY 1

RULE EEE3END
IF NODE SP PRESSURE < 0.2
THEN PUMP EEE3 STATUS IS CLOSED
PRIORITY 1

RULE EEE3ACELERA
IF NODE SP PRESSURE > 4
THEN PUMP EEE3 SETTING IS 0.98
PRIORITY 2

RULE EEE3CALMINHA
IF NODE SP PRESSURE < 1
AND NODE SP PRESSURE > 0.2
THEN PUMP EEE3 SETTING IS 0.83
PRIORITY 2

[ENERGY]
Global Efficiency   75
Global Price       0
Demand Charge       0
Pump EEE1             Efficiency EEE1ef
Pump EEE1             Price     1
Pump EEE2             Efficiency EEE2ef
Pump EEE2             Price     1
Pump EEE3             Efficiency EEE3ef
Pump EEE3             Price     1

[EMITTERS]
;Junction         Coefficient

[QUALITY]
;Node             InitQual

[SOURCES]
;Node             Type         Quality     Pattern

[REACTIONS]
;Type     Pipe/Tank       Coefficient

[REACTIONS]
Order Bulk             1
Order Tank             1
Order Wall             1
Global Bulk           0
Global Wall           0
Limiting Potential     0
Roughness Correlation 0

[MIXING]
;Tank             Model

[TIMES]
Duration           240
Hydraulic Timestep 0.0028
Quality Timestep   0:01
Pattern Timestep   1:00
Pattern Start       0:00
Report Timestep     0:01
Report Start       0:00
Start ClockTime     12 am
Statistic           None

[REPORT]
Status             No
Summary             No
Page               0

[OPTIONS]
Units               LPS
Headloss           H-W
Specific Gravity   1
Viscosity           1
Trials             1000
Accuracy           0.001
CHECKFREQ           2
MAXCHECK           10
DAMPLIMIT           0
Unbalanced         Continue 10
Pattern             1
Demand Multiplier   1.0
Emitter Exponent   0.5
Quality             None mg/L
Diffusivity         1
Tolerance           0.01

[COORDINATES]
;Node             X-Coord         Y-Coord
Q1               -3192.87         7504.05
2               -2840.14         6950.11
3               -2273.24         6961.45
4               -1921.77         6961.45
5               -1264.17         6961.45
Q2               1354.88         7494.33
7               1831.07         6961.45
8               2375.28         6950.11
9               2817.46         6950.11
10               3962.59         6950.11
11               5765.31         6950.11
12               6411.56         6950.11
14               7137.19         6950.11
1               -5.67           6961.45
6               368.48           6961.45
13               9540.82         6950.11
PS-EEE1         -3209.08         6936.79
PS-EEE2         1345.22         6969.21
SP               6434.36         7568.88

[VERTICES]
;Link             X-Coord         Y-Coord

[LABELS]
;X-Coord           Y-Coord          Label & Anchor Node

[BACKDROP]
DIMENSIONS     0.00             0.00             10000.00         10000.00
UNITS           None
FILE
OFFSET         0.00             0.00

Its a false alarm. It seems I'll only happen if you use the decimal step time. As this is not proper use for the software, it's not really a bug. Still, it is interesting how PS-EEE2 randomly fills in or not fills in.

It is easy to see the difference by using the graph report. Time series showing pressure in nodes PS-EEE1 and PS-EEE2. With hydraulic and reporting time steps set to "0:01" everything works properly and can easily be seen that the nodes follow the same pattern. If these time steps are set to 0.0028 or 0.00390625 (which is exactly 1/256 to avoid infinite decimals in binary, that could bug a comparison operation) the same graph will not show the node's pressures in the same pattern.