It has passed a lot of time since people is having this problem and for the moment Line 6 hasn't launched a new driver. It's a pitty.
If anyone is planning to buy a UX2 Studio I recomend not to do it. It is not fully supported on Windows 8.1, and also it have a biggest problem if you try to use Cakewalk Sonar X3.
THIS IS UNACCEPTABLE.