I recently upgraded to Catalina but after a few surprises I went back to Mojave using a Time Machine backup to restore data. I use Google to sync contacts on my Mac and iOS devices, and Gmail runs fine in the Mac mail app. I've done this for several years and its worked flawlessly ... until I went back to Mojave.
I’ve had no problems with contacts in Mail but after I restored Mojave I noticed contact names in Messages on the Mac weren't showing - just phone numbers and conversations. When I checked Contacts on the Mac all of my Contacts had disappeared (they're still on my iPhone, iPad and safely at Google).
In Mojave if I open Internet Accounts in System Preference the Gmail account has Contacts ticked. I’ve ticked and unticked. No difference.
When I try to add a CardDav account in Internet Accounts Google won’t verify my username and password even though they’re correct.
Strangely, when I open Contacts, and then Enter Time Machine, I can successfully go back to an earlier time and see all the Contacts. However, when I click Restore, and watch the animation bring them all back - the animation ends with a pause and all the Contacts disappear before my eyes leaving an empty Contacts app with the words "No cards".
Any advice on how to get my Google contacts back in the Contacts app on Mac Mojave would be most appreciated.