Leaving an area and coming back sometimes causes some or all blocks in a tank to not render liquid inside.

http://i4.minus.com/iblBmoZwfn4Lxb.png

This happens with any liquid, AFAIK. Seems to only be a rendering issue, tanks still behave normally and the rendering can be temporarily fixed by mining and replacing the tanks individually.

Thanks for the report! I'll look into it

Is this in multiplayer or single player?

This is in multiplayer.

Ok great. Thanks!

This is fixed, heres a preview:
https://dl.dropboxusercontent.com/u/4295615/OpenBlocks-1.0.0-delta.jar