Here's what is happening:
Courses that were created work great (start learning, view videos, take quiz, receive a completed page with Certification link) until later at time that a site-administrator makes a change to the quiz-unit configured in the course.
If a course quiz-unit is altered and saved, then the STUDENTS can only make it as far as the coursepress course "pre-completion" page. This means that they receive a message like:
"Message I got after taking this quiz Congratulations! You have completed the course!
Your course instructor will now review your work and get back to you with your final grade before issuing you a certificate of completion."
I have tested this on the production server and our staging server. It is currently happening on course titled "V13P04 – Domestic Violence / The Response"
The only method of recourse I have found is to un-publish the broken course, create it again anew -- Duplicating the course does not solve the broken quiz-unit issue.
Please login to the site and take a look. This seems to be a course press pro bug.