I had an issue where I couldn’t complete the Building an Army quest. I couldn’t abandon the quest, to start it again. The WQ didn’t show up. Thalyssra didn’t offer me the Withered army Training option.
I tried party sync, which didnt seem to work. I’m not sure if it’s required for it. (think it is, my buddy was at the part of doing the building an army quest).
But what I noticed is that I had a event quest still in my on screen UI quest window. You know, the quests that pop up when you fly over something etc.
You have to click it and then you get the quest on screen and need to accept it. Somehow I had like 4 quests there and when I all clicked them, the last one was the Building an Army quest, that I could complete and then the WQ instantly popped up and I could talk with Thalyssra to start the Withered Army training again.
Hope this helps other players.