Slimes can be glitchy too sometimes. Especially with high ping, which is what I have all the time. But I think it only happens if I don't land directly in the middle of it. I don't know.
Stairs are especially glitchy for me when I do harry potter, I rubberband like crazy, not sure if its the champ or what but I am always on 1.8.9. On regular maps when I'm more casual I dont have a problem though