In the one true king storyline after talking to the king I went to Nimue, got through the dialogue up to the decision on whether to kill or spare her, I chose kill and halfway through her answer the dialogue stopped, I was taken out of dialogue mode and can no longer interact with her.
I noticed after this happened that my flyer summons were fighting a dran through the closed door, but I never got hit and I am not sure whether this was the cause of the interaction issue.
Restarting the game does not fix.
The quest item rod of retribution is still in my inventory.
I am not sure whether the game considers her alive or dead.
Build ID: 16182387
#Cannot kill Nimue
fringe rock
tacit agate
you're probably going to have to reroll the adventure 
you likely got taken out of the dialogue due to combat
fringe rock
Yeah I gave up on it but thought to report anyway.
Every other time I got hit while I was in a dialogue the game didn't close it so I found it strange.