Anonymous login with @angular/fire does not work in Ionic project for iOS

I have an Ionic Angular app using @angular/fire/auth to perform anonymous sign-in on iOS. The function is called, but it never resolves or rejects. On Android and in the browser, it works fine.

public async loginAnonymousUser() {
  console.log("FUNCTION LOG IN ANON");
  return await signInAnonymously(this.afAuth)
    .then(() => console.log("SUCCESS SIGNING IN!"))
    .catch(error => console.log("LOG IN ERROR:", error));
}

What has been checked / tried

1. Firebase configuration

• GoogleService-Info.plist is in ios/App/App and found via Bundle.main.path
• Bundle ID in plist matches App → TARGETS → General → Identity → Bundle Identifier.
• Plist target membership is checked for the app target.
• firebaseConfig for AngularFire matches plist values.

2. Xcode / iOS setup

• Opened App.xcworkspace, not .xcodeproj.
• pod install run, and FirebaseCore module compiles correctly.
• FirebaseApp.configure()is called in AppDelegate.swift.

3. Network / ATS

• App Transport Security settings checked; network calls succeed.

4. Other

• Verified plist is found and correct.
• Verified auth.currentUser is null before sign-in.
• Works on Android, not on iOS.

Any other ideas what to check for are welcome. I am out of ideas, and AI has proven worthless so far.