If you don't have pressure sensitivity there is probably a driver issue. The easiest way to check for pressure is to use the ink pen because it reacts strongly to pressure changes, so double check with that (it can sometimes be harder to see in other tools) and if you don't see anything you probably need to reset drivers to the default. If Realtime Stylus is turned on and the drivers are functioning correctly there should be no reason that pressure would be lost on the stroke.
Matt
ArtRage UI
Ambient Design.