Why are classes in Markbook inactive?
This occurs when a timetables import update has been done wherein the class_codes differ or create a new database ID upon import. This can happen if you have class codes that differ between terms or semesters.
The inactive flag represents that the original Class_ID for that particular class has changed since the original assignment of that class to the markbook, so Staff need to be aware that if a Refresh Classes/Students is done against that markbook, the students within the inactive class will be moved to the 'Left' tab of the markbook for manual reinstatement to the markbook.
If the markbook does need a refresh, then it's best to advise Class Teachers of any inactive classes to ensure they pin students to the markbook to prevent them from being moved over to the 'Left' tab in these instances, OR alternatively, get them to FIRST assign the new class ID for that class grouping and the students (and marks) will move from the existing inactive class over to the newly added Class ID.