I'm having the same issue on iOS 26, with a non-Unity, native GameKit game. The authenticateHandler callback isn't called, and trying to show a GKGameCenterViewController freezes the app. I don't have the issue on iOS 18.4 simulator. The console shows: Could not create endpoint for service name: com.apple.GameOverlayUI.dashboard-service Failed to create GameOverlayUI Dashboard Remote Proxy