It appears that when a forum post is rated, it still appears in the AJAX marking guide as an item that needs attention.

Additionally, when an essay question in a quiz is created that does not have any points associated with it the item disappears in the marking guide block once saved but when refreshed it appears again as an item requiring grading.

Sometimes teachers will add essay questions to quizzes to provide opportunities for feedback and reflection but they will not be graded portions of the quizzes.