How do I prevent Flirc from executing remote key presses when not using it?

[mjunk]

Hi everyone. Hope I can get a solution for this frustrating problem I have. First, my setup is 1) Samsung TV, 2) Bell Fibe STB, 3) Yamaha AVR and 4) 2019 Shield TV pro. Several years ago I purchased a gen 1 Flirc USB which at the time I was using a Chromebox with Kodi on it and worked flawlessly with my Harmony One remote. Fast forward to today and that Chromebox has been replaced with the Shield. I've set it up just fine except for one small problem. When using my STB remote key presses will be picked up by the Flirc and wake up my Shield or  launch apps if already awake. Although I've spent many hours and done extensive research on this I can probably eventually find a fix but just want some answers to these questions to guide me the right direction:

1. Obviously I have to set up the Flirc as a device in the Harmony app but do I also need to set up the Shield as well?
2. Do I program only in the myHarmony app or do I need to use the Flirc app?
3. Probably asking this in the wrong forums but does anyone know how to put the Shield to sleep?

Thanks for any help. I've read a lot of "solutions" but they aren't very clear.