Correction: thought Outlook "old" and Outlook "new" were two distinct software packages. turns out it's the same! you can switch it by going to the "Outlook" menu.
reverting my OL 16.58.22011705 it re-gains it's capability to work with Exchange Server on-premises AND showing a working index :))
blunderbusses
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
From
Zurich, Switzerland
Post
Replies
Boosts
Views
Activity
Updating to 16.58.2210904 DID NOT help as our mailboxes are on on-premises Exchange servers which are not yet supported by New Outlook!
If you try to add your account you'll be greeted by the wizard saying that Exchange Support would be "coming soon"