And now for some good news ... I think!
It looks like M$ has updated the OS to handle webcams though I've seen no news reports to confirm it. I re-downloaded the webcam software from Logitech and tried again last night and low and behold it now appears to be working. So, I'm not sure why there has been no reporting of this or just how complete the fix is or what exactly the fix is, but for me at least my C910 webcam appears to be working now.
Brian