Similar search failures with On My Computer mail folders with questionable interplay between Spotlight on MBP 14 (2021) M1 model a2442 macOS Monterey v. 12.4 and Outlook for Mac v. 16.63 (update 22070801) after I used Migration Assistant to set up the A2442. All suggested remedies (e.g. no exclusions in Spotlight/Privacy no special characters in Profile Name) ineffective. Any restored search functionality. e.g faciltated by removal of Outlook.sqlite from Users<username>\Library\Group Containers\UBF8T346G9.Office\Outlook\Outlook 15 Profiles\Main Profile\Dats\Outlook.sqlite forcing Outlook to rebuild its DB, only sporadic and temporary. I surmised that Spotlight’s indexing and thus disharmony with Outlook may be the culprit IN MY CASE (Cant stress that enough) and I forced Spotlight to rebuild Using Terminal app. I switched Spotlight off and on again with the following steps: 1.     Open /Applications/Utilities/Terminal.app 2.     Enter the following (entering your password when prompted, you may need to have your user password available on a Text Edit pane so you can copy and past it):
 sudo mdutil -a -i off 3.     Enter:
 sudo mdutil -a -i on After executing the above commands searching in Spotlight for a known word in an Outlook message triggered the Spotlight indexing process. Progress could be observed via a progress bar immediately under the Spotlight search topic. I have a 360MB Outlook database and it took about 90 minutes to reindex. Thereafter the Search function in Outlook was fully functional in all categories, e.g. Mailboxes and Contacts. I found the initial hint to reindex Spotlight here: https://moof-it.co.uk/how-to-fix-issues-with-outlook-search-in-macos/ Hope this helps DR