I have tried everything mentioned and still can’t see Anduin in the throne room. I have already completed the Darkshore questline and party sync doesn’t work for me even when I group with someone who can see him. I tried doing the Argus intro quests to see if maybe I would get Anduin instead of Turalyon but that didn’t help either. Stuck here and don’t know what to do.
EDIT: So after grouping with 6 different people and doing the party sync I finally got it to work. Its important to group with someone lower level and have them be lead in the group and then do party sync. Finally got Anduin to continue on the quest.