Have you tried restarting Thunderbird in troubleshooting mode to see if you sill have that issue? (it is on the help menu)

I have the same problem after Thunderbird update. Search in address book doesn't work completely, even in troubleshooting mode. If I type something in search bar and hit the enter button or search icon nothing happens. The entire address book is visible and I can scroll it down. I tried to restart Thunderbird, restart the computer but still the same. After last update my address book disappeared and I had to import it from .mdb file. Maybe it is connected somehow.