THis part took about 10 to 15 min just had to let it sit and monitor it. After letting SARA create the profile After a few minutes all the connections would start changing from Clear to BEARER. Running thru that and just telling SARA to continue to fix the issue and get to a point where it asks did I want it to recreate the profile I said yes and that also did it. I ran MS SARA and chose outlook keeps prompting for credential which also happened. I found another fix as well but its more time consuming. How can you tell? If you open Outlook Connection Status, under the AuthN field if it says clear (Legacy Auth) If it says Bearer* (Modern AUTH). The issue that caused this was Outlook2013 stuck on legacy AUTH and not using Modern Auth. I reached a point where I am down to 2 users left with this issue and our help desk has been pushing out Outlook 2016 which has Modern Auth on by default. I was never able to put my finger on it, nor was MS for that matter which is sad! It would be nice to be able to put my finger on it and just delete that part without having to delete the entire user profile. So, the autodiscover and setup process is storing something in the users profile or User registry that do not get deleted just by deleting the Outlook profile. Logged back in and Outlook now connects ok.

Knowing it would work I now backed up all data from my own user profile and deleted that. This time Outlook connected to Office365. I deleted the entire user profile off the RDS server and logged in again. I deleted the Outlook profile but still could not connect. I tried connecting the account using an Admin login account which I knew had been used to access a different users Office365 account but never my account and definitely no account with MFA enabled. I was able to connect outlook to Office365 on another computer and so knew the MFA was working. I checked the Autodiscover settings in the Domain Controllers DNS server and they reflected those in the public DNS. I ran into this problem on our RDS server which runs alongside a domain controller in Azure.

Mfa outlook