Thank you Sam but I do not believe this is the case.
As noted in my original post, I am using a modern well specified computer.
I have previously used a number of different USB 2.00 items on the this port without a problem, including my DSLR camera + USB 2.00 cable for astroimaging and, as demonstrated, this 1600+EFW camera does work using the USB 2.0 cable. Using other USB 3.0 items the port also works OK without any problems.
It is only the ZWO 1600+EFW that does not work properly.
I can therefore only conclude that either this camera has problems with certain ports, for whatever reason? Or the USB 3.00 cable may not of sufficient quality.
I will continue to look into this problem and would appreciate any further help but this is the second ZWO camera I have purchased (previously a ZWO 120MC) and have been disappointed to have connection / USB problems with both.