Press & Hold Random Button

I have a 2008 Prius with the Nav Package and CD Changer.

According to my Instruction Manual, if I press and hold "RAND" button while using a MP3 data disc, it will "Beep" and play randomly from all folders on the disc. However, when I press and hold the Random Button, It doesn't beep and shows are playing "FLD.RAND" mode on the screen.

Is anyone else having this issue? Am I doing something wrong? Any help would be appreciated.