Harmony 665 programming problem?

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Just bought this and cannot get it to work correctly with my Signa S2.

I’m using the soundbar and an optical cable with a Samsung TV, Dish Hopper3 and an Apple TV 4K.

When I first hit the Watch Tv function everything turns on just fine and works like expected, except the Signa S2 is slow to stream any sound. If I turn the system off and come back later and decide to watch a movie on the Apple TV and I click on the Watch Movie button, everything fires up like it’s suppose to and all is good.

The problem is that if while watching a movie I decide to go back to watching the tv everything does what it’s suppose to except the Signa S2. It will change the audio back to the tv via the optical and it works perfectly for about 5 secs and then one of the lights goes out on the Signa indicating the input has been changed to HDMI-ARC. Since I am not using that input at all, I get no sound! But, if I click on the Watch tv button for a second time it switches back to optical and all is well again. I guess my main question is why is the Signa changing inputs to an input with nothing hooked to it. The Harmony is not programmed to switch its inputs, yet it does. The Logitech website is useless and I cannot get registered or signed in on it due to technical problems. Was hoping someone here may be able to help.