I’ve been dealing with a level three Sonos support engineer. He contacted me after I emailed the CEO! His response is below. I don’t see how this is a problem on Apple side when everything was working fine until a Sonos update. For me, it only happens when I use the Sonos app to access Apple Music, and I play an Apple Music playlist that I created. Most of the songs wanna play. However, if I go directly to those songs, or play them as part of the album, they play fine. it’s just the Apple Music playlist where I have this issue. If I use airplay to stream Apple Music from my phone to any of my Sonos devices, I have no issues. It’s incredibly frustrating. Here’s what the level three and Janire wrote to me last week  (I’m not sure why he refers to my problem is intermittent when it happens consistently) :

”The issue discovered with 15.2 is an Apple issue. It's something they put in a temporary fix for in late March, and have a permanent fix planned later this year. Again, this issue is a very specific issue that affects uploaded tracks, and always affects those same tracks. Whenever Apple fixes that I wouldn't expect it to help with intermittent issues, although it's not impossible that changes to fix a specific issue effect your issue.”

Here’s the best workaround.  Sonos blames this 100% on Apple; not sure I believe that.

https://support.sonos.com/en/article/stream-airplay-audio-to-sonos

So basically it'll never be fixed. I've purchased my last SONOS product. 

Regrettably, I think you might be right. I’m also not really a believer in the ‘it’s all Apple’s fault’ narrative being peddled by Sonos.

There were no issues until the new Atmos upgrade to the Sonos app earlier this year. I tested it in beta and quickly removed it when the encoding bug appeared. When I reverted back, everything was fine. That was until the Atmos version went on general release.

A botched app upgrade in order to release the Era 300 before the software was properly tested.

4 months and no solution- nobody at Sonos cares. If you look at the status page there is still a green check mark next to Apple Music. How is that possible? It does not work properly unless you attach an old sonos speaker/old amp to your active grouping?