I have both 2017 and 2019 shield tvs. I moved my 2017 shield to the bedroom and took the 2019 remote and unpaired it from the 2019 since I use Logitech setup on it. The 2019 remote every day or other day keeps reconnecting to the 2019 shield. I have to hold the back and home button for 3 seconds to get it back to the 2017 shield. Then the next morning I'll tell the 2019 shield to forget remote 2 accessory. That night or next night it does it all over again. What can I do to the 2019 remote to make it stop pairing back to the 2019 shield because obviously what I'm doing isn't working.
The 2019 has "disable shield accessories auto pair" in dev options. Toggling that on should fix it.