Azure AD B2C: Sign in with apple “Sign-up not completed”

[ali-ibnetariq]

We are integrating Azure AD B2C with User Flows. We have followed the guide found here for implementation.

On iOS side we are using AppAuth-iOS. Once we launch OIDAuthState

1. We get a page authentication options i.e Facebook, Gmail, Apple and PhoneNumber.
2. We choose Apple.
3. iOS present Apple Sign In controller. Our app logo does not appear here.
4. We authorised it with finger print.
5. Loader shows for 2-3 seconds with message "Signing in"
6. Then we get "Sign-Up not completed"
7. This is working perfectly fine on Safari (macOS Big Sur) with same steps.

We found a troubleshooting guide at this link. According to this link our client_id should be bundle identifier of app instead of service id. Once we updated it.

1. Our apps logo appears on presented Apple Sign In controller
2. We have same result i.e "Sig-up not completed". on iOS
3. This also stoped working on Safari (macOS Big Sur) which was previously working.
   

Note: We are trying to test on Safari(macOS) for verification purpose only. This won't be our actual use case.

This is probably due to configuration issue which we can't figure out. Can please provide any guidance here?