So, I was one of the unlucky few who had their quests vanish during the Galatur server incident ; -;
I had my Stronghold quests vanish and couldn’t progress my stronghold at all. (Keep in mind I didn’t start my stronghold quests at all). But I found a fix to this, what I did was create a new character play all the way back to quest where you unlock the stronghold system and song. This seemed to reboot my stronghold island and I actually saw the intro cutscenes and got my quests back. I am not sure if this will work for someone who already started quests on the island but if you haven’t and you are still looking for a way to actually use your stronghold it wouldn’t hurt to try. Unfortunately, this is a lengthy process but hey a fix is a fix 
P.S. I didn’t use a character boost and I don’t think that will work because I manually did the quest again.