I had this issue, but I’ve gone 4-5 weeks without a dropout now, (touch wood).

lg cx firmware 3.21.16 along with a different hdmi cable (Belkin ultra high speed) seems to have solved it for me, and I was getting these drops quite often when changing between devices or sources on the tv.

Im actually a little hesitant about updating to the new Sonos firmware now.

i’ve replace hdmi cables twice and it cuts on all of them. everything is up to date, LG C7, Apple TV and Sonos Arc.  if Sonos  support resolved this issue for Samsung, they should resolve it for LG TVs. 

Hope to solve at Sony TV too...

I have tried 4 different hdmi cables and all my firmware is updated (arc, lg b9 and Apple tv 4k). But im still having complete audio drops when im switching source - that includes going from my Apple tv to the tv tuner but also when switching channels. 
 

For now i can get the audio back by switching to the TV’s speakers and then after a few seconds it will change to hdmi and that will “trigger” the audio to “come back” to the arc.

Have the same issue with LG CX and Sonos Arc in 5.1 configuration. Switching inputs often makes the sound stop completely. Only a reboot or switching inputs a few times helps sometimes.

This was my issue, it’s really strange how it seems fixed for me now, really odd. As I said above latest cx firmware and new hdmi cable and not had dropout for over a month.

so how do we get support like Samsung TV thread?  

I have the slightly older LG C9 OLED running on LG firmware v05.00.10 and no audio dropout or lip-sync issues at all with that current build.

I’m running the TV with the Sonos Arc, surrounds & Sub connected via HDMI-eARC. The digital sound out is set to ‘pass-through’, rather than ‘Auto’. The HDMI input audio format is ‘Bitstream’. DTV audio is set to Auto (default).

Do you have any hardware connected? Apple tv? 
 

I have the same settings and im having audio drops 5-10 a day. It happens when i switch source and i have a theory its connected to audioformat. So when i switch from 5.1 to 2.0 the audio drops completly and i have to remind the arc its getting a audio signal.

Yes, I have an Apple TV.  Why hasn’t Sonos Support been on this thread like the Samsung thread?  

I have Apple TV 4HD, Firestick 4K, an old PS3 and a Virgin Media Tivo V6 cable TV box - so I use a HDMI switch too, but no sound drop/sync issues at all with the C9 - I’m not using any special cables, just those that came with the devices, but all my devices are wired to an unmanaged ethernet switch back to the router. Not that I think wiring makes a difference, as I’ve tried the Apple TV on WiFi in the past (and that really makes the connection quicker) as the ethernet port on the ATV4 HD is only 100Mbits/s, but I prefer the stability of a wired connection.

The Sonos Arc however is running on my WiFi (WM:1), as are both the surrounds and Sub (WM: 2)

I guess you’re lucky then 

Have you tried setting up the HDMI handshakes again with your devices by powering everything off completely (not standby) for a minute or so? Maybe consider changing your HDMI cables too if the problem persists. Faulty HDMI cables are certainly not unheard of.

One other ‘minor’ thing - did you setup the Sonos Arc in the LG ‘Device Connector’ using ‘Sonos’ as the Soundbar Manufacturer? (See screenshot from my TV). I’m not sure it will make a difference, but mention it just in case.

Tried everything and nothing works. 
 

Are you working on the issue Sonos?

Do you get drop outs if you use internal apps like Netflix? If so, can you try internal apps with the Apple device unplugged, or is it purely happening only with the apple device?

Yes i did. Before i got my ATV 4k i had drop out when switching from Netflix (or other apps) and to the tv tuner. Now i mostly happens when switching source (ATV 4k to tv tuner). But it also happen when i switch channels and i guess its related to the signal. If i switch from a channel with 5.1 to a channel with stereo i’ll get audio drops.

But can you watch say an entire film without any drops?

So if you don't switch inputs and just watch something, will the entire thing play with no drop outs ?

Can you jump on the network matrix on the link below. Change Sonos IP for whatever IP your arc is using. 

Change some inputs and see if it goes red or anything looks problematic. 

​​​http://Sonos IP:1400/support/review

It only happens when i switch source. 
 

I cant access the link and i have no idea about network matrix and what it means. Everything is connected with ethernet by the way.

If you check “About My System” from within the Sonos app, you can get the IP address for your Arc.  If it was “000.000.0.000”, for instance, you would enter the following into the address bar of your browser:

000.000.0.000:1400/support/review

That address will take you to some links for each Sonos unit you have and there is also a “Network Matrix” link that will show the status of all of your units.  Red areas in the matrix indicate problem areas due to interference, etc.

I am not sure how relevant this is for ethernet only setups but just adding some clarification as to what it is...

Ok I can see it now. No red areas. My surrounds are green and my arc is grey (maybe because of Ethernet?).

Still no issues? Im thinking about trying the same cable but i dont know if its worth it…

Have you solved the issue/been in contact with Sonos support? I tried getting an answer in the samsung thread but was just told: “All I can recommend is that you make sure your LG TV is up-to-date, you contact LG if issues persist, and that you please keep LG related queries to LG related threads.” Quite a bad answer if you ask me. 

has anyone purchased the new apple tv 4k and seen if this issue is resolved?

Just got the new Apple TV, same issue. In contact with support via email and their response didn’t work. Contacted again and they sent the same fix (again). Might just ditch the sonos, way too much effort when these things should be plug and play and stay out of the way (at least for me).