Where are your speakers? Not only your home theater speakers, but where are the speakers that are in the tv?

Did you change anything since this problem started? Anything at all was moved around the tv? Such as candle holder that is made a metal or whatever. Some that was made a metal that was on top of the tv for along time? Besides the change of ir codes via the remote. Which by the way is not the suspect, the ir code that you are using does not cause anything like this. I do not have a compass right now, other wise I would test my screen on the top and bottum of the screen.

Were you there when the tech came by to degauss your tv? What did they do, did they take apart the tv or what? I am not sure what the exact procedour is to have the tv degaussed by a tech. But I do know this, each time your tv is turned on, by any means, the tv is degaussed each time.