USB music - Shuffle All not working

Hi guys,
Wondering if a) its just me and b) anyone have a solution

I have connected a Verbatim 16gb "Clip it" USB stick with all my music on it.

Plays no problems in browse mode. Can move around the folders no worries.
Works in shuffle folder mode no problems.

Put it in shuffle all mode and it eventually stops working.
Eg it will shuffle for a while (so far this has varied from 1 to 15 songs before it locks up)
It will be playing a song, and then just keep on repeating that song. The track back and forward buttons (both on the steering wheel and on the touch screen) don't work.

Occasionally Ive found by turning shuffle mode off all together, tracking forward through a few songs, and then switching out of the audio screen (e.g. to nav, phone or home screen) then back into audio, putting shuffle all back on will unlock it, at least for the short term.

As you can imagine, this process is a little frustrating to do while driving.

Tested if it was just my usb drive - by trying the same with my phone connected by usb cable - same problem.

Tested to see if maybe it was the number of files - e.g. was 16gb of mp3s just too much for it to shuffle through. Nope - does the same with only 500mb of mp3s in various folders.

If this is just me - what should I expect from the dealer - is there such a thing as a software update or factory reset for the stereo system?

I haven't tested it using a USB, but used the shuffle on my ipod and it ran through a whole album OK.

My son had this problem on his Ford Kuga also disabled his voice control he had to turn off the shuffle then it worked fine.

My evoque does this in shuffle all too, normally when it starts playing crap tracks and i start skipping them. It seems to confuse it.