Sometimes, Canvas and Synergy don't quite agree after the grade passback has been run, and running the Sync process again does not appear to fix anything. In these cases, there is a way to tell Canvas to forcibly update and re-synchronize every score for every student for a selection of your assignments. This process is called a Remaster. It's a very powerful program, however, and you can accidentally synchronize things you didn't want to. Please read and follow these instructions carefully.
Enable Grade Sync Menu Item
When you have your Course pulled up in Canvas, you should have a Grade Sync menu item:

If you have this menu item already, then you can proceed below to Running the Remaster Process.
Otherwise, to enable the Grade Sync menu item, follow these steps.
- First, pull up the course in Canvas that you're having trouble with.
- From the menu at the left, choose Settings from the very bottom of the list.
- On the Settings screen, switch over to the Navigation tab.
- On the Navigation tab, you'll see a group of active menu items at the top, and below that a group of disabled menu items. Find the disabled menu item called Grade Sync.
- Click the three dots on the right side of the Grade Sync item and choose Enable. It should move to the group of enabled menu items at the top.
- At the very bottom of the screen, click the Save button to save the change. The menu item should then appear immediately in the list to the left.
- Proceed with running the remaster process below.
Running the Remaster Process
With the Grade Sync menu available, we can run the remaster process. Again, this process is very powerful, so use it with care.
- Go to the Grade Sync screen.
- On the Grade Sync screen, go to the Utilities tab. Quick aside: On the Utilities tab, you'll see a little slider called "Nightly Sync". You can turn that on and off from here. If that's turned on, Canvas will try to sync assignments every night automatically. You may or may not want that enabled, but in many cases it helps.
- On the Utilities tab, click the Remaster Grade Passback button.
- A window will open to configure the remaster. WARNING: By default, the system will try to remaster all assignments for all sections, including those that do not currently have Synergy synchronization enabled! Be careful from this point on. You can click the Close button to back out before starting the process.
- From the Filter by Section drop-down, choose the section to synchronize or choose All Sections to synchronize all sections of that course.
- Then go through the list of assignments and verify that only the assignments you want to force a remaster on have the checkbox selected.
- When you're ready, click the Remaster Grades button to start the process. You'll be taken to the History tab on the Grade Sync page where you can see the process running and it will be listed when it has been completed. The process will take a while to run. I have seen a case where three full sections of a course with about 30 assignments took about an hour to complete. (It was about 2,200 individual scores to remaster overall).
Canvas also has instructions for doing this.