If you try to place sand/gravel in the air, it wouldn't fall.
This one should be pretty easy to say.
MC-239786
Sand/Gravel Gravity Breaks Beyond 16 Bit Integer Limit
Resolved
Awaiting Response
0
Was this screenshot taken in a vanilla environment? In your other bug report, you were running Forge. If you are able to reproduce this issue without any modifications to your game, please attach a screenshot with the debug screen enabled.