Same issue for me here with no troubleshooting fixing it. Mine just doesn't allow YouTube Music to be played at all due to no playlists being shown, and no songs or albums appearing when using the search function under YouTube Music in the Sonos app. 

To anyone in the future reading this or those still currently having this issues, just use the brave browser app go to https://music.youtube.com/ login and airplay (iOS) from there - No ads, all your saved playlists, albums, liked songs etc, will continue to play when phone is locked/app is minimised and you don’t have to be a premium YT music subscriber. 

Sorry if you have already been asked this: 

do you see more than one accounts/handles in YouTube or when adding the account in Sonos?

I had that exact issue when I first added YTM and used my “YouTube username” handle when signing in. 

I then deleted the YTM in Sonos app and tried again and this time signed-in with my google email address which appeared to be the “primary” account. Then all searches work and content plays without issues. 
 

The obvious downside is that since I use the “username” handle in YouTube and had playlists stored in YouTube, I won’t now see those in Sonos as they are on that other account. So if I want to save playlists in YTM I need to be logged in with the primary account and those show up fine in Sonos. I can live with this “two account” issue, though. 

When adding YouTube music, I see both of my 2 accounts that I have for YouTube on my phone and was having the issue on both accounts I tried. Surprisingly though, after having my main account connected but not being able to see any of my playlists or search for music for a couple weeks, it randomly started working when I tried to use it yesterday, so that's been good. Not sure what caused it to finally work and what was keeping it from working before, but I'm pleased with that now, and I'm definitely not disconnecting it for fear of it happening again. It also wasn't a VPN issue for me as I was hoping prior. 

I can see all of my music streaming providers, I can see everything in my music library, I can see all of my products, but when I go to play ANYTHING, it tells me “something went wrong” and nothing is playing. No kidding something went wrong!! When I try to play a Pandora station, one of my Spotify or Amazon Music playlists, it just spins indefinitely. At least two days ago it would play anything I have...then it kept telling me it couldn’t find any products (I have 6 different speakers). Today I start the app, and it has my services, playlists, and products, but won’t play anything. If I didn’t already have so much invested in the products, I would IMMEDIATELY switch to a system that works consistently. 

Come on Sonos, PLEASE!!!

Nope. Only ever had one YouTube music account, its the only one I’ve ever had linked to the Sonos system. I’m still finding the same issues with the same albums from the first day of the May update. 

I’ve tried de-linking and re-linking my YouTube account. I’ve tried to factory reset speakers. None of its helped.

I am now having the same exact YouTube music issues again out of nowhere. Funnily enough, I can still play from it from the playlist I last had hooked up to my system, but no playlists or anything shows up when I hit YouTube Music within the Sonos app, and I'm not able to search for anything. This is just so bad. 

Hi

I'm having issues today, I have 2  accounts and tried to add them both via ytmuisic but still can't access any playlists or search for any songs, have tried unlinking and relinking multiple times but still not joy

Hooray! Two weeks ago a Level 2 help desk person in Costa Rica connected my iTunes library to Sonos in about 20 minutes. Now after 5 months I am finally able to listen to my personal song library with Sonos. Hopefully it will be several months before a Sonos software change will disconnect me again. 

I'm pleased for you but why have you posted on this thread?  This is to do with not being able to play music from YouTube music! 

Yup won’t play any music. The new app is garbage; anyone want a free 24 set of useless speakers?