Prompts for MFA across OneDrive, Teams, Outlook

isotonic_uk Hello, even though Moe_Kinani replied with a workaround that historically fix similar issues with authentication it shouldn't be used anymore. As for the prompt it most likely shows as the "remember device" service setting is ticked and it's configurable 1-60 days **edit** (just checked and its 365 now). I understand the customer has CA in their subscription so they should be able to work around this to either exclude managed devices, trusted locations, sign-in frequency etc. and not use the remember mfa service setting.

The WAM/ADAL issue

https://docs.microsoft.com/en-my/office365/troubleshoot/authentication/connection-issue-when-sign-in-office-2016

As for your question "60 days" (note the admins update)

https://feedback.azure.com/forums/169401-azure-active-directory/suggestions/35055382-mfa-remember-device-permanently-remember-per-d

Sign-in frequency
https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/howto-conditional-access-session-lifetime 

To assist in reviewing your settings

https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa-mfasettings

Hope it helps.