Has anything been resolved on this bug? I am running 810 Alpha2-Latest and have the same problem.
Standard, Basic Orbiter screens show more than one floorplan correctly, MDs with UI2, with or without Alpha-Blending, flash the additional floorplan if you can catch it, then only display the first floorplan. The objects for the additional selected floorplans are there if you hover over them, where they should be, and, you can even control the lights, for example on the second or third plan, but you are looking at the first floorplan while doing this blindly.
Thanks,
Charles