After moving and setting things back up we seem to be having a bit of an issue.
We have a sound bar that supports ARC; it's a Signa S2 to be exact.
The 65S4 also supports ARC (HDMI3).
The TV remote does change the volume on the sound bar; and the sound bar changes its volume/the TV's volume, nothing wrong there.
The issue right now is that no sound is coming through the sound bar.
Setting the input on the sound bar to TV (Via HDMI) results in no sound.
We've had to plug in the optical cord and change the input to optical just to get sound. It's not the end of the world, but it would be nice to get ARC fully working; so we don't have to use HDMI + Optical.
I just encountered this issue today. Accidentally unplugged my TV for a moment, now the soundbar won't show up again in my CEC devices on the Roku TV. Did you find a solution?
I would try Home>Settings>System>Power>restart. Especially if you have fast tv start enabled in that menu. I've read that option can cause problems because it never really "reboots." Maybe the power loss caused confusion, and the tv is stuck in the state it's in (never really powering off and booting up fully from a blank slate. Instead in a corrupted memory/hibernated state.).
That restart isn't a factory reset. You won't lose your settings. If the restart doesn't fix it, you may have to try factory reset. (I assume you've tried disconnecting the soundbar from the tv, and reconnecting it?).
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.
Turns out the issue wasn't with the TV, it was with the soundbar. I ended up performing a factory reset on the soundbar and then it immediately worked after I turned it back on. Hopefully if anyone else ever comes looking for this problem they can find this solution too. In order to factory reset the soundbar I held down these buttons on the soundbar itself: the power button, the source button (left of bluetooth), and the volume up button all at the same time for about 10 seconds until the lights all flashed, then I waited a moment and turned the soundbar back on. All good now!
I'm using the Magnifi Mini with a Roku TV TCL 65" but I hope this helps.
I had the issue where I could hear the clicks when changing the volume, but I couldn't hear the tv audio (Netflix, Menu clicks when scrolling, etc.) unless I pressed the ARC button on the Polk remote. It would happen every time I pressed + or - for the volume button on the Roku remote AND the Polk remote. I removed the soundbar from my Google Home completely and now I have no issues. That could be why the factory reset helped. But looking back, the tv didn't start having issues until I connected the soundbar to Google Home. So I suggest removing your Polk soundbar from your casting devices completel