Reproduction steps:

1. Create an assignment with a scale as the grading type in a course with users
2. As a student, submit an assignment
3. Go to the assignment as an admin and hit 'Grade'
4. Give the student a grade
5. Press save
6. Set the grade to "No grade"
7. Press save
8. Use the filter button (top right)
9. Select "Requires grading"
10. Expected: The user you graded and ungraded is displayed
    Actual: The user you graded and ungraded is not displayed
11. As the teacher, go to your dashboard
12. Expected: the user is displayed underneath the course
    Actual: the user is not mentioned

Please note: There is one more function that uses the same logic as the above, but it seems to only be used by unit tests. We must investigate this and either remove the unused code or add to the testing instructions the part of moodle that uses this code.