So, we are assuming that you’ve sent in hard data to Sonos via a system diagnostic report, and called Sonos Support, correct?

As you’ve done many hours of troubleshooting already and presumably have powered everything ‘off’ and ‘on’ again and perhaps have changed the optical cable as part of your testing …and the TV firmware has not been recently updated and there are no further TV updates available, it maybe best to submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and then contact/chat with Sonos Support Staff via this LINK and see what the Staff can perhaps suggest to resolve the matter. 

When powering-down sub/surround's the lipsync Issue on playbar does not occur.

When powering-up sub/surround's the lipsync issue on playbar is still there.

Maybe an unknown problem with Sonosnet in combination with own network.......

........issue seems to be solved after powering down hole network (router/switches/AP) and Sonos (playbar/sub/surround's) and powering up again :-)

I’m curious as to what  Sonos Support said, when you called them?

Sonos support analysed this issue and told me to contact Philips (as a TV problem)

Issue is still solved :-)

Experiencing the same challenge, getting big lip sync problems when I turn on Dolby 5.1 on my Apple TV 4k (2g) If I leave ATV on default there are basically no lip sync problems but then I don't get Dolby 5.1 only Stereo -PCM.

My setup:
Samsung 55” S90C 4K OLED Smart TV (2023) (latest firmware)
Apple TV 4K. 2g (tvOS beta 17.3. 21K5625e)
Playbar-Sub-2xPlay (latest software 15.11)

Tried ALL settings both on my TV, ATV and Sonos app, also tried resetting everything, nothing works.
All I have left is to wait for an update and hope it solves the challenge.

P.S

Was there a certain order you restarted everything?
Router-TV-ATV-Sonos or ?

@Peter_254,

The Sonos Home Theatre Soundbar can only play the TV audio (immediately) when it receives it from the TV and connected devices. Perhaps ensure the TV is not set to process the audio as it passes through the TV. There maybe a TV setting which allows the audio to pass-through without the TV processor interrupting the audio. If the TV cannot do that, then you’re best to use an audio extractor between the Apple TV and a direct connection to the soundbar instead so that the audio does not ‘pass through’ the TV at all.

Many people have success with such audio extractors and splitters which can often be found on sites like Amazon etc. Here is one example (simply chosen at random), but always research the product/check that it will work with your TV/HT setup, before purchase, as the one below and others on Amazon have various connections for different makes/models of TV and Soundbar…

https://www.amazon.co.uk/Tendak-Switcher-Optical-Toslink-Extractor/dp/B07YD2CLMY

The strange thing is that it has worked perfectly for many years, but this was on a Samsung UE55JU6075..

Bought a new TV, Samsung S90C OLED, initially there were no problems but now there is lip sync.
Pass through can only be activated when using HDMI eARC and not Optical..

If nothing else, I have a good excuse to upgrade my soundbar haha..