Ahh its pretty old then... might want to upgrade i seem to remember some other issues with the non 4k ATV
That is the oddity with an identical era ATV in the other room having none of the same issues. : ) The "live" vs recorded video is the other stumper.
All my AppleTVs are actually that 4th generation (we have 5 running). The ones on the network local to the Channels server have no issues with anything. Almost all content is OTA ASTC.
My standby is to not consider updating until Apple stops providing software updates.