Horses can cannot be lead over 1 block high elevations

Duplicate of: https://bugs.mojang.com/browse/MC-91732

Expected
Expected to be able to lead horses around like other animals. As you walk around, the terrain has 1 block height differences, for other animals they will jump up a block and continue following you if they are on a lead.

Results
Horses will no longer do this, they will get stuck on the terrain, a block lower, and never jump up to follow you.

This worked fine in 1.8.9.

Steps to Reproduce:
1. Find any horse, tamed or wild and put a lead on it
2. Try to lead it anywhere