Have just run this test and it does appear to confuse some USB-C ports (my phone and 3.0 usb-C port on my laptop detect the pi gadget however the 3.1 usb-C port

Have just run this test and it does appear to confuse some USB-C ports (my phone and 3.0 usb-C port on my laptop detect the pi gadget however the 3.1 usb-C port doesn't detect the gadget if the pi is powered by gpio).