I attempted to summon FallingSand (of a specific block type), which worked, but if I summoned the Entity too far near an edge of a block, it would just stay there, without snapping to one of the blocks it rests on.

How to reproduce:
1. Stand a little over halfway off a block (holding shift while doing this helps)
2. Use a command like this in the chatbox: /summon FallingSand ~ ~ ~

I included an image showing an example of what I mean with the block not "snapping" into place correctly.