The bug

Falling blocks should break if they fall on torches and slabs. This, however, appears to not be happening. The block just stays has an entity and never returns to the "block state" or drops.

This only happens when gamerule doEntityDrops is set to false.

How to replicate

1. Put on the ground any block that should break gravity blocks (like torches or slabs).
2. Create a pillar at its side, just has a guide. Count 2 blocks up and place sand.
3. Torches will be completely covered by the sand, and will stay on top of slabs (as you can see on the screenshot bellow). You won't be able to break the sand until it really hits solid ground and returns to be a solid block.