Probably a rare bug that disrupts pathing

Might be the save file where it's happening
Might be the save file where it's happening
Might be the save file where it's happening
Might be the save file where it's happening

Was doing the first pet dungeon. Scooped up a handful of enemies from the toybox and deposited them near my arena where they got into a fight with my other creatures. Soon all the regular enemies were defeated and hauled off to prison. My troops continued to fight with emberlings and thunderlings for about 5 minutes or maybe more. They seemed invulnerable but might have been spawning copies and timing out repeatedly; it seemed like there were more of them at some times than others. My troops didn't seem to gain any experience from this 5-minute fight.

After that, my arena emptied out so I looked for beastmasters. They were at various parts of the dungeon and it said they were "training beasts". My dungeon has a moongate every 10-15 squares, and the arena has a moongate at each end. The beastmasters were wandering back and forth, often taking moongates to other random moongates all over the dungeon. Sometimes they even found the arena but then got sucked back into the moongate. I watched for about 10 minutes and the arena was empty most of the time; occasionally a beastmaster would get to the arena and throw a couple beasts in, but he wouldn't be there long before he was once again making the moongate tour. I had cast recall on all of them during the elemental fight because it said a beastmaster is unhappy.

Watched for another 10 minutes and it's basically the same but whenever a beastmaster occasionally finds the arena it throws in about 6 beasts before wandering away.  I hovered over one that was dropping beasts and it was "working" instead of "training beasts".

Other creatures also sometimes take a moongate to somewhere, then get sucked back in, possibly because they came out on the wrong side and decided they wanted to go the other way or something. Necromancers and wizards standing near a moongate often had their summons constantly getting sucked in and reemerging from the gate.