### SOLVED ###
With thanks to my colleague Craig he spotted the problem and found the solution.
I was missing something in my device_add.
qm monitor 101
device_add usb-ehci,id=usb,bus=pci.0,addr=0x4
device_add usb-host,id=usb999,vendorid=0x1058,productid=0x0701,bus=usb.0
I was missing the...