When you have a user who will have student-like interactions in a course, but is not actually enrolled in the course, unfortunately they appear in the gradebook. There is no way to block this. When the instructor is monitoring completion, grades, etc, they will constantly see a user a who has a Zero, hasn't completed the assignments, etc. This user may skew data. The user may get notifications of assignments being due, missing etc.
Examples of when this may be necessary: Peer Mentors/TAs, Auditing students
Why other role-types won't work:
Observer: there are quirks to the observer role that make it not ideal. Also, we allow faculty to add observers, and so we don't want to build additional observer-type roles that faculty could add themselves.
Designer/TA: It does not seem to be possible to prevent these roles from viewing *unpublished* content in the class. Which opens the door to academic dishonesty
Create a student-based role that does not appear in the gradebook (and ideally, is not "assigned" any of the assignments, but can view them if they are published and unlocked).
Basically, this role should see the course exactly as a regular student does, but can have additional permissions (such as posting announcements) as determined by the institution in "permissions", and does *NOT* appear in the gradebook.
Other possible solutions
1. fix the observer role so that it is more robust/customizable. Currently, it seems to be designed mostly for parents in K-12, and that makes it weird for the many, many, other scenarios where an Observer role makes more sense.
2. Create a setting (that can be toggled on/off) in the Designer/TA role such that the user can be prevented from seeing unpublished content
