When you delete the block under the snow block (made of snow layers) will fall down, but when you place a snow layer on top of that block it won't fall down.

Steps to Reproduce:

1. Place a block.
2. Place eight snow layers on top of it to create a full snow block.
3. Place one snow layer on top of the snow block.
4. Break the block below the snow block.

Observed Results:
The snow block floats in the air.

Expected Results:
The snow block falls to the ground.