Hi @Sanooj M ,
Thanks for your post and apologies for the delay! Make sure your app is registered in the right tenant under Azure AD B2C > App Registrations and feel free to share a screenshot of your registration configuration.
If you are authenticating the users from other B2C tenants with user flows you should select Accounts in any identity provider or organizational directory under Supported account types.
If the application is already created with the Supported account type selected, you can update the application's manifest and make sure that signInAudience is set too AzureADandPersonalMicrosoftAccount . The accesstokenAcceptedVersion parameter also would need to be set to 2.
I believe if these properties are configured correctly, the app should appear in the dropdown.
Let me know if you have further questions.
If the information helped you, please Accept the answer. This will help us as well as others in the community who may be researching similar information.