Sometimes you will find that a page in your site is not displaying or giving a 404 error.
Pages outside of the main Notion page you have connected to Super will not be visible in Super for security reasons that prevent accidental publishing of your Notion pages in Super, even if those pages are Public pages.
Please check that the subpages you've added from Notion are actually subpages in Notion of your home page that you've linked to your Super site.
Once you move the page to become a subpage of the home page in Notion, the 404 error should go away. If it doesn't please contact support for assistance using the Intercom chat bubble.