@All
This is a confirmed bug for both modded and non-modded game instances first of all. The usual retort I hear from folks about bugs is that it's mods. This isn't one of those.
Second, there 'is' a way to continue forward but it limits dialogue choices.
When Mizora is stuck in this loop, visit the Iron Throne and you'll find Duke Ravengard there, but unalived. Pick him up on your shoulder and carry him out. Then go talk to Mizora. It should clear the cycle and she'll tell you she's coming to camp with a proposition. The proposition will only have two options instead of the third (which of course is to back out of the Pact & also save the Duke). Now it's one or the other, Wyll is in an eternal pact and bring Ravengard back to life, or Wyll is free and Ravengard remains dead. In some ways it's actually a more powerful storyline so I suppose good things come from unexpected places.
