We are experiencing basically the same issue this user was about 2.5 years ago. Link to that thread. Unfortunately, no response in that as to how or if it got resolved.
If I enable the Force Email Verification rule verbatim as to how it appears in the documentation, it just endlessly loops. It seems to go to our app, and then kick back immediately to the authentication page. I expected an error message to pop up explaining why the login was refused. I see the URL change in the browser quickly before the page changes, but never any error or message.
Any thoughts as to why this is happening and how to fix it?