Reposting issue after seeing several threads about the same issue, and a lot of people responding here and on reddit with exactly the same problem.
After completing the Tubbins Tea Part stage of the Ember Court quest chain, the quest chain simply stops, there is no follow up and as such you cannot start the weekly event, nor obtain the weekly reward.
A few friends of mine have successfully completed it, but two have the same issue as me, we have all submitted tickets, but the response time is 12 days…
The only other thing I can add is upon completing the Tubbins Tea Party stage I got the quest reward and an achievement banner, but no actual acknowledgment I completed the quest, maybe this is the reason the next stage does not trigger.
Very frustrating after completing all the pre quests, and also the risk that we may not be able to obtain a weekly reward through no fault of our own.