I have found with people who have had this issue, removing Outlook profile and re-adding it has resolved this issue on at least 2 occasions I have come across it, if this helps.
To remove an outlook profile, Close Outlook then click on the Windows start menu > Search control panel > view under small or large icons and find 'Mail'
Click on Show Profiles, default just says Outlook, click remove, then apply, then OK.
Open Outlook and enter a profile name Outlook is ok to enter here, and restart machine or Teams and re-start/launch and then it should be ok again.