If you have the release level, try tools>import>import a file>import addressbook>import sqlite and then select the abook dot sqlite file from your release profile (while thunderbird is not running. OR, if you're comfortable in Windows File manager, copy abook.* from the release version and paste in same location in beta version. I regret you had this difficult.

I tried lots of things. I got a 100 contacts from Gmail but that is a small fraction. I had contacts sorted into several ABooks. with 3 gmail accounts. I gave up and went back to the old Mozilla TB. When the contacts and signature issues are solved I'll try again. Thanks