After completing week 4, I never recieved the quest step to start week 5. I've double checked my quests tab, and haven't found it. In fact, the seasonal tab is empty. I've also checked the quests vendor in the tower with no avail. As a little theory, my wifi isn't the best, so it's possible that it happened to cut out right as I would've recieved the quest step. It would've had to have been short, since I don't remember getting disconnected, though it was a while back since I was hoping the issue would fix itself. The quest is still availiable on my other characters, but I'd rather not have to do it over again.