sand on fences will node drop a sand block but becomes stuck in the falling animation

What I expected to happen was...:
I expected the sand that had fallen onto a fence to either break or attach to the top.

What actually happened was...:
The sand would remain stuck in the falling animation but not remain a solid block.

Steps to Reproduce:
1. place a fence under some sandstone or any block that does not fall.
2. place multiple blocks of sand on the non-falling block.
3. break the non-falling block