Lesson in Rise locked up

While editing a lesson in Rise, it locked up my entire course. I exited Rise and re-entered it and still couldn't get in. Eventually, I was able to duplicate the course and get into everything except the one lesson. When I get to that lesson, it completely locks up everything even in preview mode. I tried to delete the lesson that was causing the problem. However, it doesn't give the delete option (seep graphic below). How can I get this to work? I'm on a tight deadline.