yeah I have the exact same problem in that the phone is not charging. Heck even while its on charge overnight and not powered on with no sim in it for 12 hours it still said 6 percent battery after 12 hour charge.
I did a hard reset and now it says 72 percent but after 4 hours of charge its still on 72 percent so something is definitely NOT right.....
Oh and by the way this is my THIRD HTC one X in two weeks and they've all had the same problem!!!
Not the charger or cable either as i've now got 6 different genuine HTC chargers and the problem is the same regardless if you use PC usb or mains wall socket charger.
NOT AT ALL IMPRESSED WITH htc one X !!!!!!!!!!!!