You apparently missed the notes at the bottom of the page you provided the image from:
Windows: “WinTV 8” (for WinTV tuners) or “AVerMedia TVBox” (for AVerMedia tuners) software might conflict with Plex Media Server’s use of the tuner. If you have issues tuning channels, please remove this software, install only the driver for your tuner, then attempt to scan channels again.
I would suggest uninstalling the software that cam with the tuner, reboot, and then install only the driver for the tuner.
Thank you for the pointer. I did attempt to only install the drivers by pointing windows at the drivers folder the DVD. However Windows reported no suitable drivers found. So I did the full install. I expected that only one program could have control of the USB device at any time, and I “assumed” that not having the AVer MediaCenter running would be enough.
I will try removing the software tonight and see if that helps.