Apple Mail Version 13.0 (3594.4.19) Search has stopped working since I upgraded to macOS Catalina (v10.15).
Mail Search fails to work on my MacBook Pro (15-inch, 2016) and my MacBook Air, both immediately after upgrading the OS. A third MacBook whose OS I have not upgraded does not have this problem, and Apple Mail Search works just fine on it. iCloud Mail Search also works fine. The problem is confined to Macs running macOS Catalina.
I notice that sheng qi k posted the same problem a week ago, just after Catalina was released, and has received no reply or comment.