Why am I unable to use Game Center on a jail broken phone? On a black iPhone 4, I open the Game Center application and it is stuck on "loading":



For a moment I assumed that it was a problem with Apple. Well, no, because turns out I have a white iPhone 4 where Game Center does work.

I heard that if an iPhone is jailbroken, you can't use Game Center for developing applications on sandbox mode. However, it does work for normal games. Both of my devices are jailbroken.

Why might my black iPhone be stuck on "loading" within the Game Center application, while the other device works just fine with it?

There is a difference in iOS version though. The black iPhone, which is stuck on the loading screen, is 6.0.1, while the white one, which works, is 4.3.3.

I already tried rebooting the black iPhone and killing the Game Center application.
iPhone 4 GSM Black:

I had the same issue when I updated to 6.1.2 from my previous version 5.1.1 when the evasi0n jailbreak came out. I solved the problem by restoring to the factory default. Then I went through the beginning steps of the iphone introduction, when i open and logged in to gamecenter everything came through pretty smooth... I jailbreaked it after I restored  and gamecenter still worked smoothly. Then I restored to my last back-up and opened gamecenter after it all loaded up and everything is still working fine.
Hopefully this simple troubleshooting helped out. It did for me.