When an order is preserved too much, they just flat out stop attacking. Also, to make sure the problem isn't in your ally triggers, check what players they are assigned to and that the right players are there.
If they keep stopping then they must be allying up, then unallying. It sortof works this way for humans, if a unit is told to attack another unit it is allied to, then the you set that player to ally then they stop attacking. So there has to be some sort of triggers that keeps allying them, then unallying them, and both are preserved.