That sounds like one of the many screwed up things that can happen as a result of Larian’s approach to stealth and combat. See, eg, Wormerine’s post in this thread: https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=837520#Post837520.

"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"