Problem: Partners may be receiving an error relating to GDAP for “Unable to get Microsoft access_token. Request failed with status code 400 calling”. This can be caused if the account that authenticated the parent has an MFA code associated.
Steps to Resolution
Check the MFA type of the account that authenticated the parent to confirm that it is set to Microsoft MFA
Check any conditional access policies you may have with additional MFA bypass or restrictions in place and remove the account if needed
Outcome: After making changes to the CA and MFA policies you should be able to authenticate the Parent Inspector once more.