The only way I was able to get a build validated was by. Unchecking Game Center from my Certificates, Identifiers & Profiles -> App ID Configuration Regenerate Provisioning Profiles Re-archive & Upload This is less than ideal but it might satisfy a time-sensitive situation ... Weirdly enough, my leaderboard/achievement features are still working on my Test Flight build.

I'm also facing this same issue. Is there a solution?