Would definitely agree it happens more in MP, 100%. Very irritating but if you can fix that I only have one more bug to moan about!

I dont think so and it seems random aswell because I have dropped two beasts such as two skargs early game to train (No other creatures around or anything), one gets K0ed and then magically spawns outside of the arena and goes to the den to sleep and recover & eat, then the other one is in the arena still and he just jumps out of the pit and strolls off to the beast den like a good little boy :P. It seems completely random and must be a bug, I noticed it happens less if you build it in a perfect square rather then an odd shape (due to the map and what you are able to build).