Missing Grades
Often times when assigning assessments to individual students, grades that were previously displayed for everyone else disappears. The good news is that MyCanvas protects student data.
In order to retrieve missing grades in your course, you will need to navigate to the quiz and or assignment itself > click on the Assign To button > select the +Add button from the side menu tray > select Everyone else in the Assign To field > input previous dates into the appropriate fields > click Save
Resource
Canvas Guide: Assign Everyone Else