Using PS360+ with Xbox doesn't work (in Soulcalibur II)

So I just got a PS360+ to put into my stick. It works fine so far with my 360 and in PS3 mode on PC, but I cannot get the stick to work with my original Xbox, either plugging it in or forcing Xbox mode by holding down 2K. I’m using a USB-to-Xbox adapter with my USB cord, which worked just fine with my previous MC Cthulhu setup. Does anybody who’s managed to use one of these with an Xbox help here?

ETA: Did some further testing and this seems to be a Soulcalibur II issue - it works just fine with Street Fighter Anniversary Collection, Dead or Alive 3 and a few other Xbox games I own. Hence the title change.

Just out of curiosity, are you supposed to be forcing xbox mode when using the USB-to-Xbox adapter? I connect my ps360+ to my xbox via RJ45, so I can see why forcing it to xbox mode seems right for my set-up. But I always thought those USB-to-Xbox adapters were expecting things like PC peripherals.

I guess this is all bunk if it works with other games and not SC. Sorry I couldn’t be much help.

I didn’t need to force it in SFAC or DOA3 (or the Xbox dash for that matter). But forced or unforced gets me bupkis in SCII.