I think this is a a reappearance of something I reported before we had this OU list. I couldn't find the earlier bug to reopen.

Go to the Gradebook.
Observe a list of students.
Click on 'First name' or 'Surname'

...and see the tutors of the groups appear in the list.

In my example I have two groups. One tutor per group. Both appear in the list.
I also have one 'course staff' member. The 'course staff' member appears in the list too.