A small number of HTC One X units aresuffering from a message notifications bug which forces the user to open up the messaging application in order to see if there are any new messages. The bug prevents the status bar from showing that a message has been received and also does not allow a badge to show up on the messaging icon on the home screen to alert the phone's user to a message.
Although the problem comes and goes and is not constant, it forces users to open their messaging app if they want to read and return messages in a timely fashion. HTC is aware of the problem and is said to be working on a fix. Although an exact date of the launch of a fix is not known, it is expected to roll out ASAP. And in case you were wondering, yes, the AT&T variant of the model is also affected.