OAuth2 fails after upgrading to 1.18.x

I have just upgraded to 1.18.x and now my OAuth2 fails to work.

When clicking the button rather than login into the admin console it now takes me back to the login page for the user
https://support.mydomain.co.uk/

Nothing has changed in the plugin, I have even disabled it and created a new OAuth2 connection, it still fails
https://docs.osticket.com/en/latest/OAuth2/Google%20Authentication%20%28SSO%29%20Guide.html

Instructions checked and followed to the letter.

Has anyone else had this experience, all was working fine with 1.17.x

Checked PHP error log and there are no errors.

Did you upgrade the OAuth2 plugin as well? Also, have you tried in an incognito window?

Cheers.