"Open Safari" button does nothing when trying to authenticate Google account
First, let me save you all time by saying up front, this is NOT the same "loop" problem many experienced in 10.14.4. I experienced that as well, but it was resolved.
Today the domain for our company's G suite account was updated so I decided to delete the old account and re-authenticate the new email from scratch (wasn't confident it would "just work")... when I get prompted with the "Google requires you authenticate with Safari" message and click "Open Safari", the button turns grey and does actually launch the Safari app, but nothing happens. If Safari is already open the button just turns grey.
Worse, I tried some of the proposed solutions for the old fix (deleting OAUTH tokens from google in my keychain) and now ALL of my google accounts (I have several G Suite accounts) require auth and NONE of them can successfully get to the auth screen in Safari.
Help please?
MacBook Pro Retina