When I use the Rift on my tablet, certain games (e.g. RiftRacer) don't work at all (after the Unity splash screen there's just a blank screen with 'trial version' written in the bottom corner).
For the Tuscany demo, it shows it as a single image, and not as the dual warped images it should be showing. However, when I open up the settings box on the demo, it shows the box twice as it should. So the demo is half working, half not.
When I loaded the Tuscany demo, head tracking doesn't work, and the image is a singular image. So, I assume it's something wrong with the USB connection. If it makes any difference, I've tried connecting it via both the USB2 and USB3 connection, and neither works.
And it definitely isn't a faulty Rift as it works on my computer (apart from a few small problems in the other thread I posted).
Make sure you don't have the Oculus config tool running when you run the game. Only one application can use the headtracker at a time, so leaving the Oculus config tool running in the background will block any other game from working.