Ocelots Unataming With Tamed Skin

I don't know if it happens in survival, but in creative, when I tame ocelots from spawn eggs, it works fine. They tame ok, and behave like tamed cats. After about a week (real time) they untame all of a sudden when I join the game, and run around, glitching between standing and sitting, and keep their tame cat skins. They can be retamed.