We use Google SSO. When we were testing the system we did not have "enforce SSO" enabled and the Google SSO button worked fine. We turned "enforce" on right before going live. SSO now does work if a user clicks on SSO button, or just enters their email, but ironically when we turned on "enforce SSO," the Google SSO button STOPPED working (even though that is the kind of SSO we are using).
When a user tries to use the "Google" sign on button they are given the following error message "Your account is enabled for Single Sign-on. Please use Single Sign-on to sign in with your company credentials" which puts them in a sign-in error loop. This is a problem because our users know that we use Google SSO and so are all trained to use the Google sign on button on all of the platforms that we use, so this is creating a lot of confusion.
I put in a support ticket, but they said that that is the way the system was designed. This is however a flaw. It seems to me that the system should recognize if the SSO is Google based and allow Google sign on if Google SSO is enabled.