Hello @LindaTernes, 

Are you experiecing that just the last student is not visible or that you have no scrollbar visible at all? There is a known issue with the Gradebook not showing the last student in the course (or cutting off half of the last student). Our work around for this has been to activate a Test Student in the courses and that becomes the last student that isn't completely visibile. Not a perfect solution, but gets the grading done here at the end of the semester.