I play in a skyblock world, and most of the platforms I have made are of bottom half slabs. I mostly save and quit on a bottom half slab. Sometimes when I log back in, the slab underneath me will fail to load and I fall to the void. This does not happen all the time but has happened to me multiple times and I lose all my stuff.

To reproduce the bug: Open a void world (or a skyblock/oneblock map). Place down some bottom half slabs(cobble stone slabs in my case). Stand (make sure you are not flying) on the slabs and save and quit. Then join back to the world.

Observed Results: The slabs will not load and you fall to the void and die.

Expected Results: The slabs will load and you should be standing on it.

Notes: This does not happen every single time. It started happening to me when I started making progress and there was a lot of built terrain to load.