When importing, are you choosing the option to Remove all Dates or Shift Dates? If the latter, there is the possibility that the wrong year is selected by accident, forcing everything to get marked late. If your grading policy is set up to automatically mark late work as missing with a 0%, this could cause what you are seeing.
Without seeing your course, it is hard to say if any specific things occurs. A few possible tips (maybe this helps correct your issue, maybe not):
- Always use "Remove Dates" when importing. As a Related Arts class, I sometimes have to punt and adjust due dates. Sometimes, I am not running things in exactly the same order or time frame each time. All of which makes shifting grades more work in the long run for me.
- When setting up the link to Powerschool:
- Go to Assignments Page and create groups that match categories on PowerSchool.
- Choose to Sync to SIS and match your PowerSchool categories to your Assignment Groups on Canvas
- Go to Grade Sync in the menu and turn on the Nightly Sync option. For me, this typically occurs around 10 - 10:30 PM local time.
- On the Grades page, go to the settings menu (Gear icon). Change the Grade Posting Policy to automatic instead of manual.
- I set my Late Policy to auto assign a 0% for missing grades. I do not use the auto deduct option for late assignments.
You might try going to Grade Sync and choosing the Remaster Grades option, just to see if that helps fix anything. That was a fix two years ago when we were having some issues on our end.