Check your side quests. I noticed tonight during Noble Lady that Tor Falk had an exclamation over his head, checked him and it showed that I unlocked some areas (that were already showing for me). after checking side quest, i went to bjorn mirwalis and it unlocked arena ( which was already unlocked also)... It could be an issue that something from that isnt registering and has caused the icon to become hidden. Hope this helps.