My Stronghold was attacked by Drakes and some Xaurips, including a Priest. I'm not entirely sure what happened during the chaotic fight but afterwards, my hirelings were hostile to me, possibly because I hit them with a spell by accident or because something converted them. The problem is that now all hirelings are hostile forever, no matter what I do, except one who shouldn't even exist (I killed him during the fight, yet there he is inside the main hall).
Dismissing and reaquiring hirelings doesn't help and some of them don't dissapear anyway: Any new people I hire are instantly and perm