I have searched, yet found nothing:
Whenever an enemy uses Charm Person on my party, they just stand around hostile. I.e. they get charmed, get a red circle 'neath their feat and the "Charmed" status icon, but they don't persue or even attack other party members! This makes Charm Person (And other charms aswell, I suspect!) not much of a threat!
I suspect this is ToBEx doing as it seems the most likely. I am not sure however!