Hello @BruceMayhue,
In beta, I have attempted to duplicate this problem by cross-listing the enrollments of an already existing section and course shell with another already existing section and course shell.
After doing the cross-listing, I was able to set a default grade (10 points out of 25 points) for an assignment that none of the students had not completed.
All of the students (21 students in the section that originally existed in this course shell and 20 students that were in the section that were cross-listed into this course shell) received the desired grade.
After you reported this to your institution's Canvas team or directly to Canvas Support?
-Doug
