I think Dave_s might have identified the issue as the device identifies itself as USB 2 to Windows who will try to use USB 2 mode and fail.
I boot Ubuntu Linux and Dave_s noticed my speed was like it was in USB 1.0 mode and it runs OK.
I can't find a driver setting to make a port use USB 1 only. I can use Linux or a SD card reader to avoid the issue, but it would be nice to get it (the firmware, even if it only ID'd it ran in USB 1.0) fixed.