Has anyone solved this issue? I just installed my Q80T TV and Q80R soundbar today. Roku Ultra which I've had for a year or so. All my cables are correct. I have the same exact issue as others here. First time I turned everything on it was awesome. Went back to the home menu for a second. Returned to movie (Rogue One) and zero sound.
I have not been able to fix it. Although I did try that audio leveling setting and I thought it was fixed, but I noticed Atmos no longer works. I don't think it's because of that setting but no app detects Atmos anymore. I have all audio settings on auto detect. Even forcing dolby dts plus still won't get Atmos going.
I read somewhere that "Leveling" changes the audio out to stereo. Not sure if that's true but that could be the issue with your Atmos.
It's incredibly frustrating. I assume it has something to do with both systems. The samsung ARC connection and Roku as well. I might try new cables but that doesn't really make sense. Cables wouldn't work for one movie then stop all of a sudden.
It seems to be related to it switching back and forth between levels of audio/video quality. I discovered another issue with HBO GO. The refresh rate kept going nuts and causing the screen to go black. Corrected it by disabling the auto adjust display refresh rate setting. Then the video worked but the audio started doing the same thing within HBO GO. I give up. I guess I'm just going to use the Samsung Apps or take my whole setup back and get a TCL TV and save the money I spent on this TV/Soundbar combo.