Honey blocks don't pull entities downward when pulled by a piston

If you put an entity on top of a honey block, and then push that honey block with a piston in any direction, the entity gets pulled along with it. Except for if you'll pulling the honey block downward. The entity then just falls off of the honey block.

The recording was too big to directly upload, so I uploaded it to YouTube:
https://youtu.be/SuMOhcEzceg