I just bought a new USB drive to sync my files between systems and hold all my music - 128gb - very nice!
I was having a problem where I could not access the drive, it took several minutes to 'load' and then claimed to be empty on one system, but on the other it worked perfectly fine, almost instantly showing the files, etc.
As it turns out, anything that 'touches' the USB drivers can cause these drives to not be recognized or to be seen as empty.
According to research I did on the web, several programs can cause the issue, Samsung KIES for accessing Samsung phones, HTC Monitor - for HTC phones, Sony PC Companion, Sony Play Memories, and a few others, including VMWARE VSphere, which was the culprit in my case.
I have VSphere installed, and the VMWare USB Arbitration Service was causing the problem. I had to open an admin DOS window and type :
sc stop "VMUSBArbService"
at which point I was able to set the service to manual - I may end up having to make it disabled, and remember to re-enable it if I want to share a USB device with any VM, but I do that so rarely as to make it not a problem.
Another strange bit - the drive worked perfectly if I rebooted the computer and inserted the drive after the opening Windows screen. I think it was getting recognized before the VMWare service started.
So now it works fine, and I learned something new about VMWare and USB devices.