there's a similar bug in the drake quests on stormheim, i will try not to spoil for the people that cares about that sort of thing, last quest in the chain has 3 requisites to complete, one is to get on the drake, second one is to do X and third one is to gtfo with the drake.

you can do part one and two, but the last requisite of the quest will not complete 80% of the time if you are on a team doing it in paralel, you have to drop quest and pick it up individually.