I've got the very same problem. The fight starts, and after the first orc vs. human battle, when the surviving inmaculates go chasing the orcs in other zones of the map, everyone turns hostile on me.
If, despite that, I try to kill every hostile character, there's a an orc that remains invulnerable no matter what.
I cannot try the trading 1 gold workaround, as you're supposed to do it with a companion and I'm in a double lone wolf game.
I've been expecting Larian to fix this for some weeks, till then I cannot progress.
