Hey there, Chuck9988,
Thanks so much for using Apple Support Communities. We want to help make sure that Spotlight is able to provide you with the best possible search results, including that data in your Outlook folders in Mail.
You mentioned that you've tried some suggestions already; was rebuilding the Spotlight index one of the suggestions that you tried? If not, then we believe it's a great place to start. This process can help resolve issues with Spotlight search results: Rebuild the Spotlight index on your Mac - Apple Support. In addition to working through those steps, we also want to recommend that you try rebuilding the mailboxes directly in the Mail app as well. This will specifically help Mail in providing you with the most accurate search data possible. You can find the steps for that process here: Rebuild mailboxes in Mail on Mac - Apple Support
We hope this does the trick for you!
Cheers.