Cat slides and moves around area after detaching a lead.

When my cat is sitting down, and I detach my lead from him, he starts moving around the area as if he's walking, but stuck in the sitting position. I have to repeatedly sit/unsit over 3 times to un-glitch him and be able to lead him before he gets too far away.
Also, it looks like one of my cats just disappeared. They won't teleport to me when I get far, and they weren't in the sitting position when it happened. Cats are really buggy in 1.14.

Version 1.14, Windows 10 Minecraft, on my Realms server.