Thanks for letting us know, JT0142,
If you haven't already, we'd suggest that you rebuild your mailboxes if you're unable to search Mail: Rebuild mailboxes in Mail on Mac - Apple Support
"Rebuild mailboxes in Mail on Mac
You may need to rebuild a mailbox to update the list of messages it contains. For example, if messages appear to be missing or garbled, or if you can’t find all relevant messages when you search using the Entire Message search option.
- In the Mail app
on your Mac, select a mailbox in the sidebar. - Choose Mailbox > Rebuild."
You can also rebuild the Spotlight index on your Mac if you're unable to search in any app: Rebuild the Spotlight index on your Mac - Apple Support
We hope this helps you.
Take care!