This is the one I originally posted about which is on UK Amazon and in stock. 
GeoHN.G 8K Fiber Optic HDMI Cable 1M

Do you have a link please? I searched Reddit and found nothing. 

Yeah unfortunately it says unavailable for me on that one, probably because it doesn’t ship here. Was looking for alternatives.

Just to put another confirmation in the thread, GeoHN.G 8K Fiber Optic HDMI Cable 1M worked for me. 

Basically as other posters have said, use the cable with the ‘display’ end plugged into the Sonos and the ‘source’ end plugged into the TV. I’ve used this for little more than a week and had no problems with it. 

Well, I've been using the hdmi 8k cable solution for more than a month and there had been no problem. This week LG updated its firmware and the cutting problems returned, be careful with your update, I'm talking about firmware 03.33.15. It seems that the problem is LG, or at least that both companies hate each other. 

15.4 is out now, I’ve installed it on my system but not tested it yet. Prepared to be disappointed though. 

Can confirm drop outs still happen on 15.4. 

The dropouts are back again, completely randomly.

Turned on the TV and they’re suddenly back after several weeks that they were gone.

Nobody cares apparently.

Neither Sonos nor LG got back to me even after contacting support multiple times.

This was my first and last Sonos product.

Completely embarrassing service and support.

I was just in a chat with Sonos support, who said to purchase a CEC-less HDMI cable to fix this issue. Which is ridiculous as everything was working fine for me until recently. I’ve noticed that the HDMI 1 port on my LG CX isn’t affected by this bug, it’s only HDMI ports 3 and 4 but if I switch the HDMI cables then HDMI 1 is affected. 

So a few months ago we had confirmation that Sonos were investigating this issue - can we get an update @Corry P?

I remember about the same time somebody had a response from Sonos saying that they were committed to resolving the issue - did that person ever get a follow up from Sonos support?

I was that person and no nobody ever contacted me back.

Well the Sonos mod did say “Please don't expect an immediate resolution” on the pinned response from 2.5 months ago. And this thread is nearing its 1 year anniversary. Wonder what the word “immediate” means in Sonos Time?

Hi @ste_ms 

Unfortunately, I have no further information to share at this time.

When I wanted to order the cable recommended a month ago it was out of stock ,other options were quite expensive so I decided to try taping pins 10-12 with a sliver of tape as suggested by @RANDUSR23296 , see page 13 of this thread. HDMI2 does not show the Sonos screensaver anymore (no signal) and I haven't had any audio dropout anymore since 1 month ago. I have not noticed any adverse side effect. If you don't have the cable and/or can't find it you might want to give this a try (be careful though).

Hi @throwawaybeam2 et al

We now recommend you reach out to the TV manufacturer (LG) as this behaviour is also occurring with different soundbar manufacturers (so it’s not a Sonos-specific issue).

Alternatively, please utilize different audio formats from McLPCM 5.1 (e.g., McLPCM 7.1, DD+, etc).

I hope this helps.

Hey Corry, if that’s truly an LG problem how come the Arc works perfectly fine? As well as any other sound bar I’ve tried except for the beam 2?

What Sonos seem to be ignoring is that this became an issue specifically after one of their software updates. 
 

why is it so difficult to get them to look into the issue and acknowledge it. 
 

have now told multiple people not to bother with the Sonos beam due to this issue

Would be helpful if anyone has links to any discussions about other manufacturers’ soundbars exhibiting the same symptoms, or knows what those sound bars have in common in their eARC implementation that my AV amp and the ARC do not.

I bought my beam and LG from the same shop and both are still under warranty so I guess I still have the option to attempt to send both back and see what happens. I believe other users have already contacted LG. 

Hi @OmriP & @mjsound 

I personally really don’t know much about it - I just found the information and shared it with you.

A search will reveal that many people with these particular TVs and all kinds of (non-Sonos) audio equipment experience the same. Here are three examples:

https://www.avforums.com/threads/lg-c1-oled48c16-issues-with-5-1-lpcm-over-earc.2422032/

https://www.reddit.com/r/LGOLED/comments/v9ly92/lg_c1_after_new_update_033006_uncompressed_51_and/

https://discussions.apple.com/thread/254122268

The issues also coincided with an LG firmware update for these particular models, and LG are actively seeking videos and other evidence from their customers in an effort to troubleshoot.

So you’re saying LG is aware and is actively working on fixing this?

Is there any way to get in touch with the team that works on this to send them videos, diagnostics etc?

Because every time I tried to contract them they responded once after several days then simply stopped answering, it seems impossible to contact them.

Hi @OmriP 

So I was informed; it’s not something I found out for myself, so I don’t know if this came from LG or from their customers. 

Sorry - I have no idea.

None of these linked issues are even remotely similar. 

Lmao what a shitshow. Skimmed the links:

1st link - PCM 5.1 no sound but DD 5.1 has sound. Turning the TV off and on again fixes the issue

2nd link - BOTH PCM 5.1 and 7.1 does not work

3rd link - Multichannel issue with ATV4K. Sometimes sounds do not come out of correct channels

Most seem to be generic uncompressed audio (arc vs earc) issue. Could be hardware/software, or could just be misconfigurations. But definitely not the HIGHLY SPECIFIC issue we are experiencing here i.e. everything works with Beam Gen 2 except PCM 5.1 which has a dropout every minute. PCM 7.1 works. Sonos Arc works.

While the provided links do not include exhaustive testing and only discussed limited use cases, it is safe to say that “None of these linked issues are even remotely similar.” You can type anything on google and you’ll find confirmations for whatever it is you want to see. And that’s just what Sonos lazily did.

I think Sonos is just capitalizing on the recently discovered cable (and to a lesser extent, HDMI1) workaround. Sonos wants to get out of this mess while the users have quieted down, already content with the solution they mostly paid for.

Edit: Who knows? Maybe one day Sonos will sell an official fiber optic HDMI cable.

Just wanted to stress one more thing: So basically Sonos is placing the blame on LG simply because numerous (dissimilar) results come out when you google for “LG OLED 5.1 issue.” Nowhere did Sonos mention that they performed a technical investigation which cleared the Beam of any wrongdoing.

Gotta admit, that’s one hell of a tactic. No need for any company to troubleshoot and honor warranties. Since you can google anything, just look for any issue with other components no matter how unrelated. Then you can simply deny support tickets by shifting blame lol.

@Corry P I’m sorry but that is a very ambiguous and seemingly dismissive response to a thread that has provided detailed evidence and diagnostics for over a year about a very specific, repeatable issue that only affects one of your soundbar models.

For clarity are you saying that Sonos have investigated and cleared the Beam of any fault in this? Have Sonos been in touch with LG?

How exactly did you find about this, ‘officially’ or just some other forum somewhere?