Can only pass-through a USB HDD over USB2, not USB3

[Husker_N7242C]

Hi everyone,

I use a pair of portable hard drive for a daily offsite backup that I take with me out of the building each day.

When I plug it into a USB2 port, I can use Libvirt Hotplug USB to pass it to the VM that manages backups but when I plug it into a USB3 port I get the following error: 

error: Failed to attach device from /tmp/libvirthotplugusb.xml
error: internal error: unable to execute QEMU command 'device_add': failed to open host usb device 2:2

I'm not sure where to start to fault-find this? I really need USB3 speed as USB2 now takes over 24 hours... .which isn't great for a 'daily' offsite backup.

Any advice would really help, thanks!
 

[Husker_N7242C]

BTW, I've tried ever USB port on the back and front of the system.