Bug found in 2.3.1:
Argg. Create a new forum, do not enable Aggregate Type for Ratings. Students post on forum, then go back and edit Aggregate Type for Ratings. Grade posts. However, no scores will be sent to the grade book.
I have to manually transfer them to the grade book.
So in summary, when you create a forum, make sure you enable ratings before anyone posts, otherwise ratings will not show in gradebook.