Sorting for missing assignments not working

[NormanNovotney]

I have an ongoing assignment due in a few days & want to check how submissions are coming along. Under grades, I see the ungraded submitted documents and dashes  (-) for students who have not yet submitted.

LARRY JONES   doc symbol

KATE WILSON    -

MARK VORHART doc symbol

GARY HOPE -

JENNY CRAFT -

GEORGE LAMP -

MICHELLE TONK doc

ROBERT SURGE  doc

RITA HEDGES -

etc,for all 150students, unorganized

How do I sort this to show all the unsubmitted students? Choosing missing assignments sort seems to do nothing

I want to see them organized:

Billy Jetsowl   doc

Mark Kwolnes doc

Wanda Tamacko    -

Larry Milestorm   -

Gorf Varderson -        

Then I can look to the left and see a coherent list of names of those who still need to submit their docs before the assignment closes