Confirmed, and you are right that it happens here too, which is the best proof it is the add-on and not your setup.
A XenForo page tells the navigation which tab it belongs to by setting a section context in its controller. The staff page never set one, so the tab lights up on no board anywhere, including this one.
It is one line in the public controller and it goes into the next XenStaff update. Thanks for reporting the small ones as well as the big ones.