I've followed all the instructions for the GameCenter stuff. I've added the code to authenticate my app, and made 3 sample achievements for my app via iTunes Connect.
I can see my 3 sample achievements in the GameCenter sandbox. Furthermore, I've added a GameCenter button that calls pops up the GameCenter sandbox GUI, and my 3 sample achievements show up when I click that button, too.
So far, so good, right?
Furthermore, I know I'm "authenticated" successfully via the API when I run, and I get the little GameCenter announce bar at the top of the title screen of my game at startup. So that's good.
And I know that my "iphone-appid" is exactly identical to the one for the app I created in iTunes connect. So that can't be the problem, either.
Here's the problem -- when I call the functions to add the achievements to GameCenter, they report success, but when I switch to the sandbox GameCenter, they do not show up.
Is the fact that I'm running an "ad-hoc distribution" build the problem here? I'm unable to build with an "iPhone Developer" signing identity at the moment for other reasons.