Hi everyone, I'm experiencing a persistent issue with Sign in with Apple on my iOS app that I cannot resolve from my side. I've already opened a support case (ID: 20000115382721) and received a reply directing me back to the Developer Forum, so I'm posting here in hopes someone has encountered the same issue or can offer guidance. Error message: FirebaseAuthException: [firebase_auth/invalid-credential] Invalid OAuth response from apple.com Critical observation: The Apple authentication screen never appears. When the user taps "Continue with Apple", the error is returned immediately. This suggests the request is being rejected before reaching Apple's authentication servers — pointing to a backend configuration issue on Apple's side for my Team ID. My setup: Team ID: DHKU23JL7H Bundle ID: com.expensespy.app Framework: Flutter with sign_in_with_apple package v7.0.1 Backend: Firebase Authentication Other auth methods (Google Sign-In, Email/Password): working correctly Verified configuration (all done correctly): App ID (com.expensespy.app): Sign In with Apple capability is enabled Configured as a primary App ID Not grouped with any other App ID Service ID (com.expensespy.app.auth): Created and linked to the primary App ID Domain: expensespy-e11ab.firebaseapp.com Return URL: https://expensespy-e11ab.firebaseapp.com/__/auth/handler All other redundant Service IDs have been removed Sign In with Apple Key: Created with Key ID X8T9NLBT4Y Linked to the primary App ID .p8 file is available Firebase Apple provider: Tested with OAuth code flow fields populated (Services ID, Team ID, Key ID, Private Key) — same error Tested with OAuth code flow fields empty (recommended for iOS-only) — same error Client-side implementation: Proper nonce generation with SHA256 hashing OAuthProvider('apple.com').credential() with idToken and rawNonce Tested across 3 different builds (Build 12, 13, 14) Tested on multiple iOS devices (iOS 18+) What I've ruled out: Client-side code (tested 3 different implementations) Firebase configuration (tested both populated and empty) Multiple Service IDs (cleaned up to just one) App ID configuration (verified primary status) Context: During my Apple Developer Program enrollment, I experienced an error that was not fully resolved. I suspect this may have left my account in a state where Sign in with Apple is not fully activated on the Apple backend for my Team ID. Question: Has anyone encountered this where the Apple auth screen never appears at all? Is there a way to verify that Sign in with Apple is properly provisioned for a specific Team ID on Apple's backend? My App Store submission is blocked by this since Sign in with Apple is required when offering third-party authentication. Any guidance from Apple engineers or developers who solved a similar issue would be deeply appreciated. Thanks!