How can I get the Submissions Field to only show data that is related to the user AND challenge of the current record? Right now it's showing all of that user's submissions for any challenge, instead of just the submissions that go with the challenge in each record.
Did you get this figured out? I looked at your base and it looks like your summary table is duplicating your Submissions table, rather than summarizing it. What, specifically, are you trying to summarize? The submissions by User by Challenge?
I think you probably need a junction table of User & Challenge, which you kind of already have.