Today I came back after a long walk through the world to find something interesting. Some hours after coming back, I went to my farm and noticed, my animals are gone. Sheeps, Chicken, Cows and Pigs were despawned (except one cow). Only my rabbits were still there.

I have no idea if my long journy through the world is the reason, this happened or something else, but my farm is nearly empty and there ist no animal near my base, except many rabbits that spawn like flies and my last cow.

Sidenote: I play on a realm. But a friend of mine plays offline and had the same problem lately.