I tried with different cables also, I am afraid it will come back (hopefully not, in that case, could you let us know the name/model of cable please?) I would understand if you wouldn't want to do it but could you unplug and plug again the soundbard ? I fear the chances of the issue coming back just by doing that are pretty high...

To be clear I changed the cable between my Apple TV and the LG CX, not the cable to the Beam. I used the stock cable supplied with the PS5 and it has continued to work fine last night and today. The original cable was the Belkin high speed one that Apple sell and recommend for ATV4K. 
 

Also the issue never disappeared for me for me after restarting or changing settings etc but disappeared instantly after changing the cable. However I am continuing to monitor it and will update if the issue comes back.

I’m fairly certain that I’ve seen the issue with just a single HDMI device connected (PS5 or Bluray) but that doesn’t mean the action of you changing the ATV cable hasn’t triggered a refresh of some cached HDMI handshake value in the TV - possibly @Fskies saw a similar thing when removing/re-adding the beam from the LG menu.

@ste_ms - Out of interest which HDMI ports do you have assigned to the PS5 and which to the ATV? To date I’ve been assuming they behave the same, but maybe some LG C1s have some buggy ports, I don’t recall if I’ve seen the behaviour on both HDMI1 and HDMI3 (I don’t use HDMI4 yet as it’s wall facing and I now have TV on a slim bracket).

Ps5 - HDMI 1, ATV - HDMI 3. I did try HDMI 4 for the ATV but the dropouts persisted. I also unplugged and replugged to try and trigger a refresh but that didn’t work until I changed the cable.

I have the dropouts with the sources connected on HDMI3, sometimes an ATV on HDMI1 (makes no difference).

However, quick look on the Internet suggests that HDMI devices don’t seem to be able to detect whether they are interconnected with an Ultra High Speed, Premium, or a regular High Speed cable (I guess that’s why AppleTV has its HDMI cable stability test suite). In any case it appears that the bundled PS5 isn’t labelled Ultra (as I’d assumed it needed to be from the tables I'd seen, but can pass 40Gbps) anyhow so probably wouldn’t trigger any special sort of refresh after all.

Mine has come back too, however I redid the steps you left here last time but I set it as home theatre instead of soundbar and it appears to be working again. Fingers crossed 
 

edit: turned my tv off and when it came back on the issue came back

Sounds like it’s an issue in the TV set somewhere. Sonos plays whatever it’s handed. 

Have you contacted the CS for the manufacturer of the TV set?

I can chip in with my experience regarding this issue. I bought a Beam Gen 2 a cople of weeks ago and had the exact same problem. Sound dropouts 1 sec every minute or so when playning Xbox Series X with uncompressed 5.1. Uncompressed 7.1, Dolby Digital and Dolby Atmos worked fine.

I have a LG C1 65” with ultra certified hdmi cable connected between the TV and the Soundbar, Xboxs own HDMI cable connected to the TV. Both the TV and the Beam with the latest firmware. I couldn't figure out what the problem was. I tried everything that I could think of, factory reset, changed cables, diffrent setting on the TV and the Xbox but nothing.

In the end I returned the Beam and bought an Sonos Arc instead and now everything works just fine. No problem with uncompressed 5.1 and I’m using the same settings on the TV/Xbox and the same cables I used for the Beam.

I didn't read the whole thread but It seems a lot of you have an LG TV (including me) so maybe there is a problem with LG and the Beam Gen 2.

i'm sorry I didn’t brought any solution to the table but I hope my input can be of some help for you guys to figure out what the issue can be.

Couldn't possibly be a Sonos bug, right? Despite the Beam 2 having internal audio buffers for lip sync, true play, multi-room, and having CEC control and HDMI handshakes and considerable DSP. Could be in the C1 too from the experiences posted, but let’s try to remain objective and keep the apologist rhetoric to the first page of these threads?

Edit: That being said I noticed there is a new LG C1 firmware released (03.33.26) which I have yet to install, will report back if this changes the behaviour of the dropouts

It’s never impossible to be a Sonos bug, by any stretch. Just unlikely. But if it were a Sonos bug, there’d likely be thousands upon thousands (relatively speaking) posts about it. 

Sonos is essentially a “dumb” device, at the end of a long chain of things. All it does is play what it’s handed, in whatever form it can, and reports back to the CEC computer on the TV a small amount of data (what type of device it is, what formats it can play, and volume info, as near as I can tell). Sure, it has those things you mention, but if they work elsewhere (for instance, on my TVs, and most other folks installations), then they should work essentially the same everywhere. 

More often than not, the issue tends to be upstream. More so before CEC became a standard, since optical, used on the PLAYBAR and PLAYBASE, was a one way transmission, but still. There’s just not that much going on in the Sonos products. 

Which is why, in the preponderance of posts I make (check me on that, look at many of my posts), I do suggest a diagnostic and a call to Sonos. Just to be sure if it is a Sonos issue, and if it is indeed a Sonos issue, providing the engineering team hard data to look at. All of the engineers I’ve worked with in the last 40 years have wanted hard data, not anecdotal data, otherwise they return quickly with a “it works on my machine” response. 

There have been calls to support and diagnostics sent in the thread. We have all reset TVs and Beam, changed cables, settings... As far as I know there is no clear answer as to what the problem is or if it is at Sonos or LG side. 

There are multiple posts here and in Reddit about this issue but there is never going to be thousands because it requires a quite specific combination of hardware and settings: Beam + LG CX and above + LPCM Multichannel 5.1 output. It is even possible that many people that have the issue just changed to Dolby if allowed by the affected device to solve it... But this is just a workaround and not always possible...

Edit

My experience is similar to many others here. My Setup LG CX (04.40.20 latest update), Sonos Beam Gen 2 (Version 14.19 latest update) with 2 IKEA SYMFONISK bookshelf speakers, PS5 & Series X. Beam is hooked up to Ethernet, 2 Ikea Speakers are on gigabit Wi-fi (router is in the room). I am using EARC, Bitstream, Digital Sound Out is Pass Through. I have 48GB Certified Ultra HDMI Cables from Monoprice. When set to Linear PCM, AV Amplifier 5.1 on PS5 I see Multichannel PCM 5.1 on the Sonos App. Dropouts occur somewhere in the 2 minute range. When set to Uncompressed 5.1 on Xbox I get the same dropouts. No issues with 7.1 on either console. Now if I set the TV to Digital Sound Out Auto instead of Pass Through and change the PS5 to Dolby, I get Dolby Multichannel PCM 5.1 with no dropouts. I guess the question is then, whats best? Multichannel PCM 7.1 and hope the Sonos Beam downmixes correctly or set it to Dolby Multichannel PCM 5.1 on both the PS5 and Series X? Non Dolby Multichannel PCM 5.1 skips on my PS5, Series X.

Just to follow up I found out setting it to auto and having “Dolby Multichannel PCM 5.1” has definite audio delay. So sounds like Non Dolby Multichannel PCM 7.1 is the way to go until this is fixed, if ever. Just sucks knowing a 7.1 signal is being sent to a 5.1 device.

If you leave the TV on pass through but set the PS5 to Dolby do you still get delay? There are a number of other discussion threads around that say that fixes the delay issue with Dolby output - on auto there is a re-encoding of the audio causing the delay I think.

That is correct, it then shows up on the Sonos App as Dolby Digital 5.1. No delay which is great but my understanding is that Dolby Digital 5.1 is lossy compared to PCM 5.1 which is lossless. Now can I hear the difference, idk lol. Maybe someone can tell if there is a discernible difference. PCM is definitely quieter, which isn’t necessarily an issue since I can just turn up or down the volume. Volume 28 on PCM = about volume 14 on Dolby Digital 5.1.

Personally I had mine on 7.1 for a while and never noticed any issue, however I don’t have surrounds. Some people were complaining that the rears weren’t mapped correctly with a 7.1 signal but I think that might have been fixed.

Also whilst I didn’t have this problem on PS5 a new cable seemed to fix the issue with my AppleTV so might be worth a try although I’m not sure if that’s just temporarily reset something that will eventually return as seems to be the case for a few people in this thread.

I don’t think it’s a cable for me, I’ve had this issue on the Series X for awhile now and just assumed it was an Xbox thing. Since then I’ve upgraded and changed out all my HDMI cables and always left it on 7.1. Just got a PS5 and found out it had the same issue. It’s definitely frustrating and makes no sense why a 7.1 signal works fine but a 5.1 signal does not. I did just test the rear speakers on LPCM 7.1 and they were mapped correctly and the same as both LPCM 5.1 and Dolby 5.1. So it may be a non issue overall. But those extra 2 channels have to go somewhere don’t they or does Sonos just eliminate them when downmixing?

Sonos have definitely said that the Beam down mixes 7.1 by design so presumably the extra channels are mixed in rather than being dropped 

Just wondering if anybody has seen any change with this issue? I have found that the issue has come back straight after the last 2 Sonos software updates but that if I restart the TV it goes away so not really a big problem but still clearly something is amiss 

I have the impression that the issue goes away more often by itself, even if it comes back... Right now audio is ok for almost 2 days... Difficult to say if this is placebo or the latest updates changed something related to the issue...

Beam 2 + LG G2 + PS5. Exact same issue with the audio dropping every few seconds, only when PS5 is set to AV Amplifier 5.1 LPCM.

After so many people here complained on the exact same issue I really don’t understand why Sonos is having such a hard time replicating it. All it takes is an LG TV and a Beam 2 with some 5.1 LPCM track.

This wasn’t an issue with my LG C9 btw. Seems like Sonos doesn’t like LG and LG doesn’t like Sonos back.

Did the firmware update fix the issue ? I am having the same issue with an LG C1 but it looks like your region got that update I am on the US and we are still on .11

03.33.26 seems to have gone missing. It installed on my A1, but not on my C1. There’s a reference to it on reddit about a month ago, but not much discussion. So unfortunately, I’ve no further observations to add yet. 

Ok so, it seems like, hopefully, I managed to fix the problem. I disabled “QuickStart+” in the TV menu, played around back and forth with some of the audio settings for a few minutes (bitstream->pcm and back, passthrough->auto and back, eARC on and off etc. multiple times) then set my PS5 to AV amplifier mode with 5.1 channels and while leaving it on and browsing the web for more info on the problem I noticed that there are no more drops in the sound (the PS5 was on the sound menu for some 15 minutes while it was idle). I found it odd so I went ahead and played a game for several hours, making sure it’s on 5.1 channels mode with LPCM, and there were no more sound drops. I then also noticed that I was not using the Sonos hdmi cable provided with the soundbar but some generic hdmi cable (because the Sonos one was too short). I went ahead and tried replacing it with the Sonos cable just for good measure as I’ve read it’s higher quality. Since then several days have passed and I’ve had no more drops. I don’t know if QuickStart+ was the culprit, or fiddling around with the settings helped, or perhaps it was even the cable, so I know it sounds a little bit like voodoo, but all of these steps together fixed the problem for me, at least so far.

Might be worth a shot for you guys too! Let me know if it helped anyone.