AD B2C access token claims missing when signing in multiple apps

Question

Considering that applications A and B are connected to the same AD B2C tenant and using the same custom policy (b2c_1a_signinup).

Problem: When signing in multiple applications, the second application gets a access token not containing the given_name and surname claims.

How to reproduce the problem:

• The user is NOT logged on to apps A or B.
• The user signs in with a Microsoft Account on app A.
• See the user name properly in the application (in the token).
• Open the app B URL and click on sign in. SSO takes place so the user is automatically logged in without prompting the authentication step.
• Don't see the username in the application (token).

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Notes:

• If the user signs in app B and then goes to app A the problem also happens.
• If app B gets a new token with a refresh token, the missing claims are present properly.

This problem does NOT happen with email & password accounts, only with social accounts,