Same issue here. One thing I noticed is that in the list of entitlements, when I submit a build via xCode to the App Store, the Game Center one is actually missing, even though it's activated in in xCode. Can anyone see the GC entitlement when they upload?

For anyone coming here doing Unity stuff, @krince advice worked for me. Deleted my local provisioning profiles and after that my build was correctly recognized as having the GC entitlements: I forced a re-creation of the automatically managed provision profiles (deleted everything under ~/Library/MobileDevice/Provisioning\ Profiles)