Can you share if you created generic forms where the students filled in their IDs since you did not have the roster in your account?
You would open the assignment and scan the student forms in that specific assignment.
If you could send a screenshot of the form to firstname.lastname@example.org, that would be helpful:
Instructions: Click on the camera icon to the right or in the Scan window, place the form under the camera (click the double arrow icon in the camera window to enlarge the window). Take a screenshot of the entire computer screen. *Please make sure the upper left hand corner of the form is visible in the screenshot.*
Which assignment is the form for in your account?