There are a few reasons why this might be happening. In order for scores to sync properly, you’ll need to be connected to the internet when you achieved the score, as well as being logged into GameCenter for Arcade. Another reason might be that only your first attempt on a daily challenge will log a score in the leaderboards. If none of those are the issue, it’s possible that you’ve found a bug! In that case, please get in touch using our Support Form, with details of which device you’re using.