Quiz with manually graded items is hidden in gradebook.
Quiz is hidden on the course page
Teacher manually grades items.
Quiz is shown on the course page.
The eye icon in the categories & items tab appears as "show"
In Preferences set "Show /hide icons" to yes.
In the Grader Report, turn editing on.
The quiz eye is open at the top of the column, but any student with a score is showing as hidden.