This all points to an issue between the source and the Arc Ultra from my perspective.  I had to get an HD Fury Arcana for my Arc to avoid passing the Audio through my TV - I’ve attached my schematic below if of interest.

Hi,

I have no doubt something like the hd arcana would help. That said  I have tried several sonos product in this very same setup (arc v1, beam gen2, sonos amp) and they all work as intended. I am fine with the limitations of no lossless sound (given my oldish tv without earc). But atmos on amazon prime sounds wonderful, when it works, so I'd prefer the issue to be addressed rather than throwing more money at the problem.

Thanks for the clear suggestion and the nice schematics though!

Btw, I've reported this issue to Sonos. I was told they were not aware, but was able to share a video I took with them. Currently waiting for L2 support.

I have the same problem but not with Apple TV but Sky Q (UK). The problem even occurs when I pause the feed.  I have no problem with Apple TV 
 

I upgraded from the ARC to the ARC Ultra.  I had no problems with the ARC and therefore not convinced with the Sonos helpdesk response that it is a Sky Q issue and not the ARC Ultra

I can’t find a reliable work around. Sometimes swapping between HDMI sources on the Tv works, sometimes changing Tv channel works and sometimes I have to power everything down.  All very annoying.

would be interested in how many people have this problem and whether anyone has found a solution 

I have a Panasonic tv with only Arc not eARC 

Same problem with the Arc Ultra and a TV Samsung Q95.

It happened before with the old Arc but was fixed after some time.

Tried reconnecting everything, reboot the TV and soundbar, swap HDMI cable, etc. After some time the problem returns.

In my case happens with the TV channels and native apps.

It's very annoying have the same problem I suffered for months with the old Arc.

Thanks for sharing your experiences. Unfortunately I have never been contacted by L2 support (which is where I was left at on Monday). I'm now considering a return, as the soundbar is unusable for me (and my family) in this state.

The simplest workaround is to force your TV  or input device to only use stereo pcm. If there's no switching of sound signal the audio will keep working.  I have forced both my appletv and xbox to use stereo, and it works OK (but of course it's bad we can't send multichannel audio to the soundbar).

My feeling is that arc vs earc is the problem here. Most people buying this soundbar probably also have an earc-compatible tv.

I have exactly the same problem. Very frustrating to say the least. I have an older but still very good tv with only arc. 
 

Every time it stops and starts any audio from the tv I have to pull wires to restart.

Hopefully someone will post some answers soon.

in the meantime I have ordered a splitter to see if it will help.

https://amzn.eu/d/7qif4FV

I have been able to use tge doundbar for a couple days without issues by setting all my devices to output stereo (except for my tv apps, as the problem doesn't seem to occur there).  So maybe that could be a workaround while we wait for an update.

The splitter will probably work (assuming it supports arc). In my experience, splitters solve some issues but might create some new ones (delays when switching input, auto switch does not work reliably, etc). But I do hope that works for you!

Same issue here. Only got the Ultra today but immediately was starting to get issues when switching between TV and recordings. Have found that pulling the HDMI cable in/out on the TV gets it back but its a bit rubbish at the moment having to do that. MY Sony TV only has ARC connection so assuming it could be that by looking at the comments. Did see on another forum about someone using a CEC HDMI blocker on the Sky box to fix their sound dropping out issue. Might be a temporary fix.

I have a cec blocker adapter, so I figured I'd try and post the results here. I disconnected all hdmi cables except the arc ultra and the Xbox. The Xbox is connected using the cec blocker. After switching Xbox audio back and forth between stereo and dolby the arc lost sound. So no, cec blocker doesn't help.

I also tried playing with the lip sync setting,  both in the tv and in the sonos app. That also doesn't work.

Overall, I can reproduce quite reliably. I would probably suspect my tv more, except that all other sonos gear I attached to the same hdmi port worked just fine (and still does). Other than forcing audio to stereo pcm I'm not aware of workarounds. Sometimes switching between different hdmi inputs also makes the sound come back.

Seems like a bug to me :-)

Had a long chat with Sonos support today running various tests, and they came back to say its working fine their end so suggested contacting Sky and see what they had to say. Needless to say after 30 minutes someone picked up the ticket at Sky, but in the last hour radio silence so I guess they are not interested.

Quick update. I spoke with Level 2 support earlier today. They have been quite helpful and they can see issues in the diagnostics. Interestingly it seems like the arc ultra is reporting a earc timeout, which is odd because my tv doesn't even have earc.

I will keep posting updates here. Hopefully we'll get at the bottom of this.

I don’t think Sky can be blamed. Other users are reporting similar problems from Apple TV and Xbox. 
 

 My system worked perfectly with an ARC and the problem only started with the upgrade to the Ultra. I only have SkyQ and AppleTv. Apple TV has no problems
 
I spoke with Sonos whose comment was that they don’t guarantee support for anything other than the TV as being the source. 
 

I offered to try swapping back to my old ARC as I still have it in another room but Sonos support were not interested as the believe the problem is the set top box
 

I also only have ARC not eARC. Anyone having problems with and eARC setup??

The timeout feels right but in my case sometimes it’s instant i.e pause for a second and restart or sometimes just change channel

The only thing I would say about that is that I played Netflix content through the app on the Sky box and it was fine, but when I went back to planner and recordings the issues started straight away. I am think that its something in the program codecs perhaps that is throwing it out. I have also tried Netflix and YouTube on the smart apps on the TV and again no issues, so I think its program content and how the ARC connection is switching between channels/recordings. I have even had it happen where the sound drops out if I dont switch, but just fast forward or rewind through the same program.

Very odd all round as had no issue with my Onkyo system.

Just to add to this conversation, when I switch the Sky box to the Normal (non Dolby) sound option in the Audio section of Sky the sound seems to work ok (or at least it seems to be on the times I have tried it), so its got to be the Dolby issue. I could leave it at that but when you spend the money like I have for this sound bar you want what you have paid for. 

I’ve forced my Tv to PCM and that works but as you say what is the point in a £1000 soundbar that you can’t use for surround sound

I have that too. But in my case I can see that sometimes, as you press pause, the audio switches back to stereo (presumably for the appletv ui) and then switches back to dolby when you resume streaming.

Just did the latest firmware update (82.2-59204) and that doesn't help.

Anybody had any luck with an earc-enabled switch?

Qmaur

thanks for the update. I’ve not had the chance to test since the update but obviously very disappointed that the problem has not been addressed

The only update I have is the CEC blocker has no impact. 
 

The odd thing is the problem is becoming less frequent and easier for me to fix. 
I unplugged the ARC from the Tv for 24hrs as I had guests staying and did not want to have to explain why the sound drops out or how to fix it. When I reconnected I had drop outs constantly either when pausing Sky Q or switching source to Sky Q. However over the past week and a half the frequency that the sound drops has reduced significantly and I can reliably address any drop outs by pausing and restarting the programme. 
I can’t think of any logical reason why over time things are improving. Having said all this it’s still a bug and still needs to be fixed by Sonos

Hi ​@Jabadahulk any luck with that splitter?

Another update. Had another chat with sonos L2 support. They confirmed they were able to reproduce the issue on some older Bravia TV. They will send me an hdmi/optical cable for further testing.

I have also ordered a splitter similar to the one linked above, only with 2 inputs instead of 4. That completely solves the lost sound issue. But, as suspected, it creates other issues. For instance I can no longer control the volume with my tv remote through the TV. It's as if the TV didn't know the soundbar was there. Also, when turning the TV off the audio will keep playing (as the TV is no longer in control).

Overall, for me the usability issues are too many, so I will send the switch back and wait for a fix.

I will report back once I receive the cable.

Qmaur. Thanks again for the update. 
 

Did they give any indication of why a new/different HDMI cable would change / fix anything?  
When I did my upgrade from the ARC to the Ultra I asked Sonos if I needed to change the cable (the Sonos supplied HDMI runs through my media wall so wanted to limit disruption) and was told that there has been no changes to the cable between the two models. 
 

Also I’m experiencing the same issues but with a Panasonic tv (ARC not eARC) so it’s not limited to Sony TVs 

I should have been clearer. They are suggesting to try the toslink adapter in the meantime, not another hdmi cable.