At this point i'm thinking this is maybe usb cable issue?
Because I've tried on windows 10 pro x64 FM53 device (has exactly the same usb driver requirement as FM11) - and it works fine.
But port is detected @ my PC:
So i'm suspecting that you are using a USB cable which has some converter chip on it - specifically "Prolific".
Could you try connecting device to PC with another cable? Ideally simple usb cable with no converters on it.