Same issue here. I've just signed to let you guys know that I have a theory why this isn't working properly. So right after I met Durance I explored every dialogue option I had (but AFTER the initial dialogue, when he was a part of my team already) and among these I've seen options and answers you listed above (and they made no sense to me at that time). So that makes me think the quest dialogue is already "used up", so the game won't let me replay it.
I know that you're working on fixing the issue, but could you give us any temporary workaround just for now? Maybe a console comm