I have the class set to 'no' for self-enrolement, we at the library enrol students to their classes.
I have come across the same problem all of a sudden twice today:
I enrol the student as usual in the class as a student and when they go to click on their listed classes they get the message:
"this course is not enrollable at the moment".
It could be something very simple, but it has never happened before and surely they would not see the title at all if they werent enrolled and needed the course to be "enrollable".