Outlook search doesn't work with Monterey

Got a new m1 16" MBP with 12.1. Did the Apple transfer from my old MBP.

Outlook can receive email, but it can't search - always returns "no results".

Searching the web and Apple developer forums I haven't found a solution that works. I've tried:

• closing an email account and re-installing it
• removing Outlook and re-installing it
• adding the relevant Outlook folder (~/Library/Group Containers/UBF8T346G9.Office/Outlook) to the Spotlight 'privacy' list and then removing it from there to try and trick Spotlight to start indexing
• Made sure that nothing Outlook related was in the Spotlight privacy area
• tried updating MacOS and Outlook, although both are up to date
• restarting

Any other ideas? Thanks.