Can't Upgrade Courses after CoursePress Pro Update

Hello,

I updated CoursePress Pro and then it asked me to "Upgrade" my courses. But when I tried to upgrade the course, it always fails. It says: Update unsuccessful. Please try again!

Screenshot: http://take.ms/90Kyq

There is nothing in debug.log regarding this issue. And I've also tried Plugin Conflict test, that also didn't help in resolving this issue.

Can you please check? I've provided all access over the chat.