Re: MAJOR GAME BREAKING BUG! Here Lies The Abyss Quest
Can't help you with what the problem is, but you can save more than just using the autosave, you know. Try to make a full save (not a quick save) before starting each mission and when entering skyhold or each major zone. Try to keep 5-10 rolling full saves. Then you can load if bugs like this happen, and try to different things to experiment with getting past the problem.
Losing 20 hours and a full character because of 1 bug due to not saving is crazy. Just be thankful you weren't 60 hours in and on the final mission.