I have a puzzling oddity that I can't figure out. I have a number of Graded Surveys (in Classic Quizzes). One of these surveys doesn't open to students until Feb 12, and yet somehow Canvas has assigned zeroes to 74 students (even Test Student has a zero). Eleven students have no grade. I can't find any obvious pattern in those excluded students. None of my other assignments are involved.
Any suggestion on what's wrong?