Falling sand does not land on shulker

The bug

If you place sand on top of a shulker, most of the time it glitches through the shulker and seems to get on top of it again but you are able to go through the sand. After some time the sand breaks without a reason.

How to reproduce

1. Spawn shulker
2. Put a wall or something where you can place sand
3. Place the sand on top of the shulker
4. Wait for the shulker to open