I've build the Apple Unity plugins and added them to my Unity project. I've also loaded up the Apple.GameKit 1.0.4 GameKit Demo Scene.
When I run this scene in the Unity editor, I get the prompt to select my Game Center account, and the username appears in the Editor Game window UI. From here, the other on-screen buttons work as well, I can pull up the Game Center Achievements window or the Realtime Matchmaking UI.
If I build this project for macOS, and run the resulting app on the Mac, it isn't working. On the game UI, the "Local Player Name" text never updates to show the username of my GameCenter account. None of the on screen buttons work, nothing happens when clicked.
If I build from unity for macOS with debug on, I can attach a debugger while running the app. If I do this, and add breakpoints, it seems that the application hits the first line from the Start() function of GameKitSample.cs :
_localPlayer = await GKLocalPlayer.Authenticate();
But execution never seems to get past this point. It also doesn't seem to throw any exception. It just gets stuck here and I can't use any Game Kit features in the sample scene.
What is missing? The same code seems to interact with Game Center just fine while running from the Unity Editor.