I know it was half a year ago, but… did you really mean latest unread post, or should that be earliest unread post? (IOW, first post after the last one you’ve already read).
(I’m mostly asking because if you’re really talking about the latest post, then “unread” seems like a meaningless distinction. It’s very uncommon to have read posts that come after unread posts, so the latest post is nearly always the latest unread post.)