Hi, Jan.
Thanks so much for your prompt response.
Yes, I had downloaded / viewed the source code for USBView some weeks ago. I was going to use it as a reference for building / troubleshooting my own code. It's only after I started analyzing the USBView source code that I realized it wasn't using WinUSB, so it wasn't much help in my efforts to use WinUSB to get where I'm going.
But since USBView wasn't using WinUSB, and USBView was talking to my devices (at least as far as getting the descriptors goes), then there was clearly something I didn't understand about the whole process conceptually, architecturally, and executionally(!). USBView doesn't get "access denied" when communicating with my devices, and I wanted to understand why.