When using strictly Folder based navigation. Being on a page within a directory you can see the path on top. When you click on some Sub Directory you land on an empty page.

If you start creating those pages so the users don't run to a dead end, the structure then gets weird.

Clicking on such a Subdirectory then leads you to the page but the navigation bar on the left breaks. You see to be in the root, instead of in the path you just clicked. On top of that if you enter the path not by clicking on the top link but via the more common navigation item on the left, the structure below that subdirectory is messed up.