Assignment

I am on Moodle 3.5.5 (Build: 20190311) and was able to make this work. The trick is to make sure your assignments are set to 'Separate Groups' in the Common Module area. I made sure that the teachers responsible for a group of students was in the same group as those students and Not in any other groups that contained other students that they did not need to be notified. They then only received submission notification for the students in their group.