The Trials of Durance not progressing

[1Lion]

I played through the game up until the point where Act 4 starts.
Durance has been a member of my party all this time, but the quest has not progressed past the following quest description:

 

 

I had a dream about Durance. My eyes seemed unable to focus on him, and a blinding light burst from his staff. Something about this dream seemed all too real - as though something in his soul was revealing itself to me. I should ask him what I saw.

 

I never went through all the dialogue with him until after I realised this at the end of Act III.
His special dialogue was present for the piece of the Godhammer, as well as during the conversation with Magran.

But I cannot seem to trigger the quest to continue on.

I have tried resting 6 times in the wild, moving from location to location in between each rest. I have gone through all the dialogue 3 times.

Nothing seems to help.

Any idea on how to get this quest to continue, or how to manually edit the save file to trigger the next part of the quest?