Unable to Start "Last Resort of Good Men" Quest

I'm about 35 hours into the game, and the last event I completed was at the Winter Palace. I've religiously talked to Dorian and this quest is still not available to me. I understand that Mother Giselle is supposed to be in the main hall to provide it to me, but she does not go there. I've completed another quest for him and done several war table missions for him with no luck. It's also been some time since I've seen approval from him (the last I recall was when i talked to him during the Winter Palace mission.

If relevant, the NPCs for my two other specialization quests are gone but still have quest markers, and Sera has disappeared from Skyhold entirely.