I suddenly found this problem today: I cannot switch page to my most important page: ‘about the company’. Like the other pages, it’s a ‘stacks page’. There is no problem going to the page via the page list on the left, but cannot do so from the list at the top. What could be causing this problem?
Just to be sure: You are seeing the page name in your navigation, but clicking it has no effect? Or, rather, your navigation does not include the page in question?
Are you sure that the “Show in navigation” box on that page is checked?