They didn't fix it in the latest huge update? Have you installed that update? I could be wrong, but I've always had to install updates manually.
Please check your Fire TV devices for an available update. There was a massive one a few days ago.
SETTINGS:MY FIRE TV:ABOUT:CHECK FOR UPDATES <-- from memory
I live in Dallas, TX, I have a very good antenna, get excellent reception but I still get this annoying popup.