It's in Polaris; I'm using it. Nice tool, lists pages that are not assigned to any category. Don't know whether it is in Sirius.

From the Administration : Category page, you click on the ? in the circle and it brings you to this page, which is cool, but some of the config options are not explained, like

Show Category Path (though this one is fairly intuitive)

and

Show Category Objects

I'm not sure the scope of those options, where they appear, and specifically what the Objects is referring to.