When one has an assignment listed in the gradebook with a grade in it, it will not delete. Users can go through the steps of deleteing the assignment, confirming that they want to delete it, then a white screen appears. If you go back to view the gb. The assignment will still be listed.
Example: f640 26744 SideID: bbd9f718-e738-4074-00ef-ac46e8f84d53