The percentage full and volume in a tank are both showing as 0 at the beginning and end of my EPS simulation, but the tank elevation or level (calculated) is shown to be greater than 0.
Check to see if your tank is set to a variable area tank. If it is change the tank type to a constant area and with an equivalent diameter.
Note that this issue is resolved starting with the cumulative patch set for version 10.00.00.55. The fix will also be included in CONNECT Edition Update 1 and greater. Reference # 739800.