Thanks @James.Morrison. I was able to figure out the problem after looking into the “Logs” tab on the Dashboard.
The issue was I was using default Google connector. 
Auth0 logs had a warning about it and on creating a new Google Oauth Client, the problem got solved. This was completely an error on my part. Looking back, a warning about Default Connector on the console might have sped up debugging. Maybe it’s something you can consider. Thanks a lot for your help!