Hi Randall,
Same page means, if you want to link to a section of the same page as your menu item. If you want to link to a section of different page.
For example: home menu links with the home page's section, or home menu links to a different(about) page's section. The same can be done with button too instead menu item.
Moreover, OnePage is a single page design, where each main menu item links to a different section of that page, so once you clicked on a menu item it scrolled to that specific section, but not redirect to any other page or window.
Would you please give us your admin access to check the issue for you?
Best Regards