Currently, when a user completes a course and tries to close it the system says they will lose progress which is confusing and deterring. It doesn't register it as complete until they close it, but I get many messages that they are afraid to close it.
I had the same problem. As a workaround, I changed the text of the pop up in the 'Translations' area, so instead of telling them they'll use their progress, it now says something like, "Thanks for completing this course. Click on the 'Close' button to register your completion status."