I am running a free version of Market press in addition to BE Subpages.
There are pages on Market press that are not real pages. I can not edit them outside of the plugin.
For ex. Categories pages, the check out page, and so on...
These pages are not actual pages and have no sub pages. The widget for some reason opts to List all parent pages as subpages on these NON-page areas.
So For the Shopping Cart it will have a list of every parent page listed in the widget as a sub page.