Folders on forum index not highlighted for new posts?

How come folders on the main forum index don't light up when there are new posts?

Related issue: Usually there's "x new" under the post count in the case of new posts to a forum, but a lot of times, for some inexplicable reason, it doesn't say "x new" even when there are new posts? So that combined with the forum folders not lighting up makes it difficult to determine when something has been posted...