Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
I had the same issue when I company implemented ADFS...
IOutlook appeared to login but would not retrieve or send emails or calendar. After googling I found community.office365.com/.../230561
but this did not help me.
I did fix it however.
In the app go into Settings->account setings-> scroll down and Clear Cache.
you will be required to type in your password again and then make a small sacrifice to Bill Gates and then hopefully it will properly synch again.
It worked for me. Although I didn't really make a sacrifice to Bill Gates. :)