Minecraft 1.10.2, Minecraft 16w33a, Minecraft 1.12.1, Minecraft 1.12.2, Minecraft 1.13-pre3, Minecraft 1.13.1, Minecraft 1.13.2, Minecraft 18w48a, Minecraft 18w48b, Minecraft 18w49a, Minecraft 18w50a
Basically if there is carpet at the bottom of stairs, mobs can't find a way to get up and just hang around the bottom or try and get under the stairs. Take away the carpet and they can walk up just fine.
How to reproduce
Video demonstrating the issue: https://youtu.be/Rrki8a2cY-M
- relates to
MC-21109 Pathfinding is fundamentally flawed (it strictly follows the grid)