Update by @unknown:
Summary:
Certain mobs cannot path-find correctly when on ladders, and get stuck there. Those noticed so far are cats and chickens.
Steps to Reproduce:
Build a small room with a ladder
Spawn a cat in the room
Allow the cat to navigate up the ladder
Observed Results:
The cat gets stuck on the second ladder block, until it is pushed off.
Expected Results:
The cat should not get stuck on ladders.
Screenshots/Videos attached: Yes
[media]
Notes:
Original Description:
Cats stays stuck on ladder on the second block.
Chickens too but less often
Confirmed in 1.11.0.4 on Windows 10.
It is intentional that mobs can climb ladders (though they do so only accidentally). However, unlike other mobs, cats don't seem to be able to get off. They just bob up and down continuously until you push them off.