This problem is described here:
http://moodle.org/mod/forum/discuss.php?d=46374#212712
Since I am admin, I can go into the database and fix this problem manually. But if a teacher didn't have access to the database, the student would not be credited with the points due to them since they aren't reflected in the total until the database discrepancy is corrected.
A few extra comments about this. The comments are being displayed correctly when reviewing the entire quiz (although not when the teacher views a student's individual question-it just says it hasn't been commented on, even though it has), it's just the points are not showing up or being included in the total.
Basically, the issue boils down to the fact that the newgraded and newest fields in quiz_states_newest table don't match as they are supposed to.
It's rather odd. I'm looking at a student's essay question that is suffering from this problem. The link says the state is 18282. However, when I open up the question, and look at all the states that are listed (1-8), the first state is 18406 and the last is 18749. When I look in the database, I see that state 18282 was the initial state created at the moment the student started the quiz! In quiz_newest_states the field newest says 18749 and the field newgraded says 18282.
The problem is that this is happening only randomly. I cannot figure out a pattern why some questions get stuck in the initial state in the newest state tableand others don't. But this really is a critical problem that needs to be sorted out.