First my disclosure is that this topic is primarily a TV one, and not ST, although my guess is the issue is software and not hardware. It does have a ST hub and its functionality to listen to dog barks- but this is not the issue now. I’ve been through the first thorough fifth rounds of poor Samsung customer support and a subcontractor technician visit- so I’ve tried the conventional channels. I’m hoping that someone here has a similar issue or one of you that knows much more about these things than I (and probably Samsung customer support) and can lead me to a solution. I bought the TV about a month ago and it replaced an older TV with the same antenna setup that I’ve used for a while. It worked great for the first month. About a week ago, when I use the OTA channels, the picture after the first second or so is distorted with dark colors on any text. It works fine on all of the other apps such as netflix. I am not getting the pixilation you’d see with a bad signal. On my own and with the techs have done the following: reset the hub, power cycled the TV, run picture diagnostics, checked most recent firmware, disconnected the wifi, moved the antenna and directly connected it to the TV (avoiding other potential wiring issues), tried other OTA channels, confirmed the same antenna provides a nice clear picture on another TV.. None of these has solved the issue. Any ideas?
Honestly, sounds like a bad tuner. I think you need to think about getting a replacement TV.
This makes total sense- did seem like an old school mechanical UHF tuner needing to be jiggled. I’m guessing it was on the mother board? The tech would have replaced the mother board if he were authorized to by Samsung. Wonder how I can ask them how to diagnose this correctly?
You may want to post on the Samsung Community Forum. 
We’ll see what they say, but so far no clear matches.