Bug Description: (Animals) float in creative mode if you float them into the air with a boat.

What I expected to happen was...:
The entity should fall when caught with a rein in the air.

What actually happened was...:
The entity remains floating in the air if you grab the entity with a rein while the boat is falling

Steps to Reproduce:
1. First step, raise an entity to the boat and grab the boat with a lead. (you must climb them to a considerable height, approximately 80 blocks)
2. Second step, release the boat and wait for it to land next to the entity.
3. Third step, grab the entity with a lead that is still up in the boat, all in the air, finally the boat falls but the entity remains floating.

I attach a video in which the error is shown more specifically: https://youtu.be/IudMUTjm1h4