For some reason, when computing student grade totals, the default in Canvas is to exclude assignments that the students don't complete. VERY FEW professors allow students to decide which assignments they want to complete. The default should treat missing assignments as 0 grades. That being said, instructors have the option to change the setting to treat missing assignments as 0 grades.
THE MAJOR PROBLEM: Even if an instructor elects to treat missing assignments as 0 grades, the students will still see their total grade computed excluding the missing assignments. They have to uncheck the box shown in the attachment in order to see their actual grade (which includes the instructor's setting to treat missing assignment as a 0 grade). This is causing significant confusion. The student believes that their grade is higher than it really is, and the instructor doesn't understand why (because they selected the appropriate setting). The instructor's setting should automatically dictate the the total grade that the student sees. A grade detail option could be added to allow students to see their current grade (only including assignments with past due dates, excluding upcoming assignments) or what if analysis.