As the title says, it's not working with Microsoft's PowerToys: FancyZones. On non-grouped windows, dragging the title window and pressing shift activates the zones. Pressing shift while dragging a gropiy doesn't do anything.
I get that this might be Microsoft's fault, but it's kind of a bummer, as I believe the kind of person who finds Groupy useful, is the same kind of person who uses FancyZones every day.