Something strange here?

We see that from time-to-time and haven't figured out a fix for it yet. It seems to be something related to one of the add-ons, in that it usually happens when new members post their first post to those threads. You'll notice a thread showing a new post, but when you click on it, there is no new post.

If you'll bump that thread with a post of your own, that will make the other post show up. Some of the other suggestions here might work, but that's what I do, then delete my post. I understand that others can't delete their own posts, but if you want to bump the thread when that happens, just report your post and we'll delete it for you.

I fixed the thread in question and the newest post is now visible.