CoursePress Preview Not Working

Hi, the "Preview" feature for the Units is not working on my site. When I click on the "Preview" link, it just reloads the page (https://www.stevefarber.com/ecourse/courses/the-extreme-leadership-edge/).

Screenshot: http://take.ms/AQO1M

I've tried flushing the permalink, didn't help. I also tried plugin conflict test, that didn't help either.

I've provided all login credentials in chat. Can you please check the issue for me?