Same deal... Works in universe 1 and not 2.
You're only going to get output with the hub set to universe 2 if you have an EtherDongle and you're sending data on Universe 2, or you have a USB Dongle and as Steve suggested, you've plugged that into the combiner or made your own adapter cable.
I'm not sure what you want to accomplish by doing that though. There is no logic on the hub or SSC's that know what universe they are on, the only thing that makes a universe 1 hub different from a universe 2 hub is the two jumpers installed to connect the correct pixelnet pair from the input RJ45 connector to the chips on the hub. If you build your own cable or use the combiner, you're effectively just testing the combiner or home-made cable and that the jumpers on your active hub work (and also your sequencer/xLights is sending data on universe 2). You're not really testing universe 2 on the hub or SSC's any more than you were testing universe 1 since the devices don't know the difference, it's all controlled by the pixelnet pair they are wired/jumpered to.
I am curious about this comment as well:
Had a few universe 2 SSCs to program. I programmed as the SS utility requires (subtract 4096, plus one)
I haven't seen the "plus one" mentioned before. If you want logical channel 4097 on your SSC, that would be channel #1 in universe #2. By your formula above, you would use 4097 - 4096 + 1 which equals 2 which is incorrect AFAIK.