While in Kuala Lumpur on a one day layover before flying back to Sydney.  I went a little bit nuts buying Kingston 512GB USB sticks from street vendors for 10MR( Malaysian Ringits) (About 3$ Australian). The USB Keys you can buy in Australia are generally from 4 - 64GB so 512GB is appreciably bigger.

So I just plugged one into my Fedora 21 box and I get.

So the fix

yum install exfat-utils fuse-exfat

Once you install the above you can access the USB-key from the default Gnome Shell File Manager