So you've claimed your event reward and you want to keep going to hit all the challenges?
We get it. There's something pretty satisfying about seeing all the challenges completed.
However, once you've claimed the final reward, that's it! The challenge has ended for you, and no more progress is counted. We're really sorry about that, but unfortunately there's no way to reopen the challenge once you've got your final reward.
If you want to see all the event tiles completed, next time you'll need to hold off on claiming your final reward until after you've fully completed the event. (But don't forget to claim your reward before the event ends!)