Course overview block and assignment overview sometimes do not list highlight submission that require grading, while the REQUIRE_GRADING in the grading table filter does. This happens for scale grades, where grade = -1 should be treated as NULL, as it is done in grading table (gradingtable.php:307-309).

The similar function that checks for ungraded submissions does not have this check (lib.php:783-802).
The second place is locallib.php:1971.

There might be other places, but i doubt so.

I classify this as a major bug because it hides actual submission from teachers, that can affect students.

I propose to implement this condition in both places. I might be able to work on that.

Replication instructions:

1. Create a course with a teacher and a student
2. Create an assignment that uses grade scale (not point!)
3. As a student, submit it
4. As a teacher, check Course Overview block and Assignment view page to see that there is one submission that requires grading
5. As a teacher, go in to grade it, and give just feedback with no grade and save.
6. As a teacher, check both the course overview block (dashboard) and the assignment's view page and observe there is no submission that requires grading.

Expected behaviour: there should still be a '1 submission requires grading' as the grade is not present.