Put the summary of the bug you're having here

What I expected to happen was...: 
When riding a horse, typically they can automatically scale up one block while running. 

What actually happened was...:
Horses tend to get stuck as they attempt to run up single blocks, stuttering constantly and shows the player floating above the horse in the process. Along with this, the horse would receive seemingly random damage when dismounting after said bug, even if dismounted on flat terrain. (Possible suffocation damage maybe?) 

Steps to Reproduce:
1.Tame and ride a horse of any variant, speed doesn't seem to matter.

2. Ride it around and attempt to climb up any one-high blocks. Seemingly random, but usually riding into corners or a larger line of one-high blocks would do the trick.

3. Dismount, see if horse takes any damage.