1. Start in a Minecraft world on a flat plane
2. Place a pathblock, soulsand, or farmblock
3. Jump onto the block.

Expected: You stay on the block
Actual result: You get pushed off the block

This doesn't apply to all non-full blocks. For example, snow layers are fine. Slabs are fine. Honey blocks are fine. Also, these blocks at-grade are typically fine; just not ones one block up.

Only the player gets pushed off. Other entities do not. For instance, villagers can be placed on these blocks, and they don't get pushed off.