I fly the c-130 in flight simulator economy where fuel economy is the key.  I found that filling all tanks to full (9800 galls) then doing a short flight of say 50 miles and after i land i find that i have 43 % tanks from 100%.  after a few of these happening i was loosing half a tank after the first flight which in FSE is worth $19,600 dollars.

To solve this i only fill to 50% or 4900 galls and it seems it doesnt register the fuel past 50% and it seems to calculate fuel ok from 50% level.  Its not the FSE client as i tested it with the 2 different clients for FSE for MSFS and I got the same results