How to get the trigger "change object stance" working?

Hey Guys! Maybe you can help me - I’m currently working on a scenario for Return of Rome and have the following problem with the trigger “change object stance”:

Somehow the enemy composite bowmen and priests don’t hold the ground, when I change their stance with a trigger to it (Guess this applies to all units, but I tested it with these two). The trigger works on my units, but everytime I use it on the AI, they follow my units after I get out of their range. The AI player is already “immobile”, but I want certain units of the AI (Bowmen and priests) don’t even follow my units after they are leaving the enemy attack range.

Thanks for your help!