I believe he's talking about the "New Posts" tab, not the home page posting of new posts. As an example, this post is not in the "New Posts," even though it's the latest post on the home page.
I think THIS is the link to New Posts.
That does work but in theory when you click on "New Post" it should display all the post you have not visited yet. Let me see if I can see anything on the backend about that. It always work for me so not sure what might be the issueI might have it figured out....If I go into New Posts and click on "Recent Posts" on the right (which goes away once I click on it), I get all the new posts, including this one.