The best answer is Not an Answer.  This issue occurs ALL the time.  Here is my experience… and a diagnostic.

Set Up.

Two Play 5’s Gen 2 and Sub Gen 2 in my garden room (aka Cabin), which is 3m x 3m.  Speakers at the front corners, sofa at the back with little in the way to affect sound.

If I perform a Trueplay tune up the Right hand channel loses all its treble and goes quiet.  The Left hand channel is fine.  Turn off Trueplay and both channels are fine but the bass is booming and the sub almost unusable, which is why Trueplay was so good before and the room sounded excellent.  The set up use to sound great until the 14.18 update.

What have I tried…

• Factory reset all three devices
• Swapped over the Left and Right speakers
• Retuned with a different device
• Stood on one leg
• Faced with back to speakers (in case I had a blocked ear!!)

Nothing works, it still sounds terrible with Trueplay on and the Right channel is all muffled.

I was about to send one speaker for repair as it was as if the tweeters had failed.  But factory reset and swapping them over in the room had the same effect after Trueplay… the right hand channel lost all treble.  And they sounded balanced with Trueplay off.

(this despite swapping the physical speakers over)

Diagnostic 240391277

I am SO glad to see this post and know I am not the only one and am not going mad.  This is the second issue this year (the Move issues were the first) where an update has affected my Sonos experience, not for days but months!

I used to be puzzled at those who did not update as soon as a new version was released.  Now once this issue is fixed I will turn off updates until an all clear is given.  Sonos acceptance testing and QA is not working.

Just came here to say I’m experiencing the same thing with a pair of Fives - Trueplay messes up and applies to the left speaker only. 

Thank you. I am hoping this months update helps, however expect it will be another couple of months.

Very disappointed as this is the second time an update has ruined my Sonos experience. Some QA is lacking in these releases. 

I also faced such a problem. And I was ready to buy other speakers because I thought my Play 5 was broken. I see that the problem appeared 2 months ago, and it is still not solved. I am very disappointed.

I have the same issue. Ran trueplay twice, left speaker gets all the volume/clarity and right is muffled.  It’s fixed when turning off trueplay.

i also turned trueplay back on, but changed the balance to +15 right and now it seems even.  Stupid fix if you ask me, but it works until the next update I suppose?

Have you supplied this hard data to Sonos in a diagnostic, and contacted them about it? They never tell us whether they’re working on something, much less if they can reproduce it, but providing them the information from your various systems might help them track it down. For what it’s worth, I’m not experiencing this issue on my various speakers. 

It's unbelievable. After several factory resets, one of the speakers stopped connecting. Now the phone is trying to connect to the Sonos Play5 WiFi network, but an error appears and an offer to connect via the Internet cable. Is WiFi broken now?

I have this issue too. Ones as rears with Arc and Sub Gen 3. Left rear often starts louder, however, if I toggle Trueplay on and off the issue is fixed, temporarily. It might play correctly for a couple of songs and then it will revert back. Even if I restart a song it will go bad again. 
i only have the system a few days - typically, how long would such an issue take to resolve?

I have the same issue with Sonos Five in stereo. If I unpair them, either one of them can be tuned with trueplay. But paired, only the left speaker

same here, brand new set of stereo Fives. with true play off left Five is slightly louder. with true play on eft Five is noticeably louder and treble happy while right Five is muffled. Sonos says they are unaware of the issue (USA) apparently have to call them later to escalate it. they initially claimed it was a network problem til they realized that my plethora of sonos products all connect and stream flawlessly. this is definitely a software issue that they need to work on 

Looking forward to hearing how you get on. I will be following up too and will post findings. Just has to be software. Also, saw some similar incidents that were reported a couple of years ago on this forum.

Same issue here with a stereo pair of Fives. 
 

Glad I found this thread. Will be contacting Sonos support tomorrow to log the issue with them. Hopefully the more reports they get the quicker it will get fixed. 

Same problem here with a pair of Play5’s, after TruPlay the sound is terrible.

left speakers seams louder, but the real problem is that the left one is much clearer (more treble) the right one is much more muffled

Have you submitted a diagnostic, and called in to Sonos, so that they have hard data to look at?

I have submitted diagnostic as has others and it is a known fault.  Hope the next release may fix this.

@bockersjv thank you for that. I’m hoping others will do that as well, in order to provide multiple avenues of tracking down the specifics, and increase pressure on it being a severe issue.  I suspect the anecdotal ‘I’m having this problem too’ aren’t sufficient. 

Same issue here. Pair of Sonos 5s in a stereo pair. Truplay results in left hand speaker being adjusted, but right hand speaker is quieter and muffled. Hopefully a fix is on its way as it used to be OK but not since last software update when I re-ran Truplay. 

I spoke with support about this. This is NOT a known issue. However, after running Trueplay for a pair of 5s in Stereo, I was advised to power off both speakers for 10 seconds and then power back on. Apparently this forces the paired speakers to share their settings and this appears to have worked for me. 

I will see (listen) if that works, thanks

It didn’t work for me… 
Maybe if they shared their settings, it shared the setting of the not-trueplayed speaker

Did not work for me also

Nor me. This is utter rubbish. Without Trueplay my pair of 5s and sub sound terrible. 

What I have found is that äfter Trueplay tuning the only way I can get the speakers to sound half decent again is to power them off.  That gets them sounding half decent but trying Trueplay again and the issues return. 
 

Jock, do you have a sub too?

Strange that Sonos told me it was a known problem, and to others they say it’s not known. How on earth can they fix it if only a few of their employees know about this? Soon 3 months now. Not acceptable for this price range… I’m very disappointed  

Me too!  I even tried to get them to read this thread but they were unwilling to do so. 

Instead they want me unsubscribe form the Beta programme, even though I’m not on any Beta activity, and try the speakers in another room, which is not a simple task.

So I moved the speakers to another room and they are still unbalanced with Trueplay on.  The removal of the Sub makes no difference nor does factory resetting and nor does doing all the same in another room in my house.  To balance the volume you need to set the right speaker to +4 on the balance slider.  Even then the treble is greatly muted on the right channel.  

I have a problem ticket open and shall be calling them later to add the above info.

Frustrating!