When I select "Group By">"Custom">"Select your Custom Treeview" and I move the "Wanted" field to "Fields added to group", XMM displays True and False in the Treeview but no movies are shown.
Perhaps it would be easier to create an entry "Wanted" in the Mini statistics panel? I often add movies as Wanted until I physically have them in my possession. Such an entry would surely make my life easier....