Mail search totally broken since upgrading to Big Sur
On my home iMac, I upgraded from Catalina to Big Sur and mail search works fine.
On my Macbook, I upgraded straight from Mojave, and mail search has been screwed up ever since. When I start typing things, it finds them in the suggestions, but when I select them, it doesn't find them in the messages.
Googling around, this appears to be a common problem, and I've tried several fixes, including deleting and re-adding the search bar. Sometimes they work for a while, sometimes it eventually works after waiting several minutes. Now it appears to be broken entirely.
I have several accounts, including a university exchange server, a Yahoo Account, and two Google accounts, and none of them work, so it's not the server, although I tried deleting and re-adding the Exchange account and it didn't fix things.
This is very frustrating, and I'd appreciate any advice.
MacBook Pro 13″, macOS 10.12