When a sticky piston is powered when it has sand on top, the piston at first doesn't seem to have powered. It makes the extension sound, however, and once it is unpowered, the sand breaks and the piston is stuck in the extended position. The piston does not have a hitbox, but can be collided with. It seems to fix when I reload the world, but when I tried something slightly different (with a slime block inbetween the sand and piston), it did not fix, but became invisible.

The latest (at the time I wrote this) versions of maLiLib and Tweakeroo were used, and I tried it with just maLiLib and in vanilla, neither had any issues. The block below on the last picture is just so I could find it again.

Do you have noTileEntityTicking enabled? Other than that I don't see how anything in Tweakeroo would break that...

I checked all of the Tweakeroo config options before creating this issue, but for some reason disableTileEntityTicking was enabled, and somehow I missed it... Turning it off fixed it; thanks for the help, and sorry for the trouble!