I have the same issue but let me go in a bit more detail. I have a few MacBook Pros. All are running Monterey 12.0.1 or 12.1. Two are on Intel and one is on M1. Outlook version is 16.56 on all machines. Lets call the Intel Macs Intel1 and Intel2. Like many of you here, I do not want to use the 'New Outlook' because it wipes out any mail folders listed as 'On My Computer'. IMO, Microsoft is trying (probably for corporate mail policy reasons) to stop users from archiving their own work mails on their machines. I have tried re-indexing spotlight multiple times on the M1 MPB (the machine that is meant to Intel 2 and has files migrated from there) As stated, the indexing starts ok (if you type in a search before starting the Spotlight re-indexing, the search will display a growing number of items. After awhile, other messages appear in results but the search term remains highlighted in the relevant mails. When mdsworker (the spotlight process) completes, the search function fails. This was true of Intel 2 and M1 MBP. The odd thing is that on Intel 1, search works fine. How can this be? My suspicion is that sometime in Nov/Dec 2021, a flag was inserted in the Outlook database to block search results from appearing. Microsoft and Apple have wasted our time and we should hear from them.

The problem is Monterey OSX 12.1 Finis. Apple needs to fix this ASAP. Its killing productivity