Undead Retreat issue

so I was doing a co-op game the other day, my secondary force of skeletal warriors and archers ready to rip apart the enemy, and I ended up having a pair of demon allies that both managed to disconnect at the same time(No idea if that's an issue, but it's not the point of this bug report, at least) Now, both of them were new, but my force wasn't too impressive and thus couldn't easily take the heat either. still, I managed to dispatch several divisions of longbeards before the enemy force proved to be just a bit too overwhelming. at this point in the battle, I sent one of my skeletal warriors into retreat to get away from a combination of enemy melee, and send them towards a group of archers.
However, at this point, shortly after stopping their retreat, and coming back under my control, a second force of dwarven light infantry engaged them and... they started to retreat again without being given orders to - until they left the map in fact. to my knowledge, the undead shouldn't retreat unless specifically ordered to, so this occurrence seems a bit off.