Very Strange! I have the x2200 with Directv, Samsung K8500 UHD Player, and now the new LG UBK90 each connected to the AVR. The x2200 is the only HDMI connection to my 55B6P, which is connected to the ARC input. No other inputs are connected to the TV. I do not have an optical connection either.
I am 100% getting surround sound through my AVR and all 7 speakers and sub watching either Netflix or Vudu through the built in TV apps, or Directv. I know it's not the TV itself I am hearing. There is a drastic difference between the 2, and the sub is on. If it was the TV, I would not be hearing the thumping from my sub. And the LG UBK90 is not turning on at all any more on it's own.
Do you think it has anything to do with the fact that I have a 2016 6 series, not a 2017 7 series or 2018 8 series? I know 2016 TV's can't do Atmos over ARC like the 2017's and forward can do, so the setup may be different. Or do you think it's because I am US? It looks like the link you sent is UK. Also, I did not turn off Simplink the way that you show in the attachment. I did it in the General settings, not Sound settings. I will look at my settings again later tonight and let you know how I have it set up.