Same, stuck here, but I do found how you can add tree view list items to it: https://answers.unrealengine.com/questions/862448/binding-data-to-listview.html
That post is about ListView, but using the same approach you can start adding data items to it. However, so far I haven’t been able to figure out how does the “tree” (and ideally it can expand and unexpand) aspect comes into play.