If you are unable to see a student’s submission in SpeedGrader after they report a submission, try the following troubleshooting tips to verify the assignment submission.
However, before you start, please ask the student to confirm the date and time of their submission. They can find this information on the assignment's details page or on the submission details page.
Note: This may not apply to external tool assignments submitted through another service. Contact that tool provider’s support for confirmation of submissions.
Review Assignment Comments
Students can upload files as part of an assignment comment. If a student is unfamiliar with the assignment submission process, they may upload their assignment submission as an assignment comment.
When you view the assignment in Speedgrader, you can view the submission details  as well as any assignment comments .
Review Student Access Report
You can also view a student's activity in your course, including submission details, from the student's Course Access Report. To view a student's access report, click the People link in Course Navigation . In the People page, locate and click the student’s name . In the student’s context card, click the student’s name .
You may want to request they send a screenshot or demonstrate in person to confirm.
Review Quiz Attempts
In cases of missing quiz submissions, you may want to review student attempts.
In the quiz details page, click the Moderate This Quiz button . The Moderate Quiz page displays a list of students in your course. Locate the student and view their attempts in the Attempts column . Canvas registers an attempt when a student clicks the Start the Quiz button.