How do I not include 0s in the class percentage average? I've chosen "aggregate only non-empty grades," but that doesn't seem to be the trick. It's not possible for students to get a 0 unless they've abandoned the quiz, which can often happen if they're trying to take it between customers. But this messes up the class average upon which my own performance as the course creator is measured.
Is there some other place I should be checking to fix this?