I was more talking to the fact that when she has 0 health, leaving the fight via flee doesn't fix the issue (she doesn't fly away)
This happened to me one time also.
Alexander disappeared but Dallis continued fighting for ever - magically regaining a small bit of health each round before I took her down to zero again.
Fleeing didn't work - the only solution I could find was to leave the fort for the marshes. That got rid of her.
