When I use the results in Course Mastery Progress - Activity Overview
It allows me to see who needs this lesson, so I don't give students busy work. I give students who have mastered the topic. The problem is, when I hit assign, the names are all covered.
One fix could be to allow me to move the popup.
Another, and a really nice addition.
If you wanted to really make this easier, have options that we could check:
 All Students:
 Not Started:
That would improve teacher accuracy for assignments.