I just wanted to mention here that I had a different audio problem of dropout for a couple of seconds every couple of minutes that was also solved by an AUTO DETECT setting. It was the Display Settings AUTO DETECT that was messing up the audio, believe it or not.
It appears that the engineers at Roku need to spend a bit of time on stabilizing the code related to all AUTO DETECT settings. They're all a bit "wonky" (a technical term )
I have a Roku Ultra and was having this problem with Xfinity app, Netflix, etc. Tried many things and then saw the fix to press "*" while watching any content; go to audio settings and switch Volume Mode to "Off". I did this and YES! It worked! Thanks!
I have a Roku Ultra playing with a LG OLED TV watching Spectrum TV channel. I always have the audio sync issue and have tried all the audio fix suggestions. Nothing seems to fix this. Seems like it is time for Ruku to look at this problem and do a software update.
Well, I spoke too soon about a fix with the Audio Mode Off fix. Turned on Roku ultra connected directly to LG OLED TV (2019) and audio sync was out of wack. I cycled power to the Roku and seems to fix sync problem. Probably only temporarily. Obviously, still a problem when watching Spectrum TV.