[1.12.2] Tank doesn't update while being filled

[MasterEnderman]

Forge: 14.23.5.2836
Base: 3.12.1
SteamAgeRevolution: 0.5.1
the tank valve shows the right amount:

but the tank is being displayed empty:

if you break and replace a tank valve (works very unreliable (maybe once in 20-40 tries)) the gui is updated and shows the fluid amount.

the same things happens if you remove the fluid out of the tank. the valves tell the right amount while the gui doesn't update at all.

Sidenote:
Fluids doesn't render inside a tank