Search in Mail stops working
I have an annoying bug in Mail on Big Sur. For a while after I reboot my iMac everything is fine but after a few hours search stops working, and so do my smart mailboxes.
If I key a word into the Search bar nothing happens - the list of emails doesn't change and I don't get the normal dropdown list. And clicking on a smart mailbox just shows Found 0 results.
I've been onto Apple support and done the suggested stuff including mailbox rebuild and re-installing MacOS. They have now suggested a nuke and pave as a last resort - which I guess means they don't have a clue. I'm ok with a full rebuild, but I wonder if the hive mind has any suggestions before I start checking my backups.....
Thanks in advance