Thanks. I verified that I can disable SSO/OpenID in Discourse and login with that same email address into Discourse. I have verified that those same credentials work with my SSO provider.
When I re-enable OpenID in Discourse, I successfully authenticate via my SSO provider but then I still end up at the Discourse screen where it wants to create an account. All three values on that screen (email, username and full name) are automatically populated by the SSO provider.
And I tried turning off all of those settings above, but no change in this behavior.