Didn't work for me either. I was added to a Team and see my Team membership at developer.apple.com and App Store Connect. For a few days it showed up fine in Xcode and then suddenly stopped showing up, giving me a sudden compile error. App owner removed my membership and re-added me. I show as having Developer permissions in App Store Connect, but it won't show up in Xcode 16 (Beta 4, Beta 6) or Xcode 16.1 Beta.