I attached the configuration I came up with for my Inteset INT-422-3 and SHIELD TV 2017. Because the USB ports are on the back, I also use an Electro 360 degree USB swivel to make the FLIRC face forward:
If the remote is already programed for the SHIELD, all you should have to do is load up the configuration attached into the FLIRC then plug it into the Shield and it should work.
-power button is a duplicate bound to OK because that's how you turn it on. You still have to go to "Sleep Now" to turn it off.
-record, skip forward, skip backwards, guide, mute, and info don't work. Fast forward and rewind should.
A better solution is apparently in the works but it's going to require a new remote (may be able to RMA for price of shipping) because FLIRC is getting a code directly. I don't know though, I'm pretty confused. All I know for sure is that the configuration is satisfactory.
NVIDIA - ShieldTV - 04918.fcfg