Google Signin dialog buttons not working

[hzsheikh]

I am working on a Windows Powerpoint add-in.

On it I have a sign in button for Google that uses oauth2.
Once the server returns the sign in URL, I am using the office-js-helpers library to create an auth dialog to open this URL, and allow the user to sign in.
While the dialog does show the Google login page perfectly fine,
none of the buttons on this dialog ('forgot password', 'next' for signing in, etc) are responding to clicks.
On trying to debug, I get a cryptic "line 458. CustomError: error in protected function".
I don't see this issue on any other platform using the same library (Powerpoint Online in any browser, Mac Powerpoint).
I have a similar button for Facebook, using an identical setup (other than the sign in URL), and no issues.

Please help shed light on what's going on here.

[sumurthy]

Is it possible to share any piece of code that might be of help to investigate?

[hzsheikh]

Unfortunately, no. I can share a screenshot:

I would assume any Google OAuth flow 'should' be able to reproduce this issue.