Hi Jan,
Thank you for getting back to me. I have been doing my development on Windows 10 with Visual Studio 2017. I've been able to get my hands on a laptop with a fresh installation of Windows 10. I was able to add debug comments to my application and compare them to what I was seeing on my development machine.
My USB device has 2 interfaces. I've used Microsoft OS descriptors to specify that I want to use winusb. My USB device's 2 interfaces were coming up correctly in Windows' device manager as using winusb. Upon closer examination of the registry here:
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB\VID_1FC9&PID_008A&MI_03\6&2ccef474&36&0003\Device Parameters
I noticed that neither of my USB interfaces had DeviceInterfaceGUIDs. Once I created these keys manually, my PC application worked ok.
Does this mean that I haven't implemented my Microsoft OS descriptors correctly?
Thanks in advance for your comments,
Regards,
Alan