Maybe Mixcloud engineers have a role too?

I guess not, since the mixcloud api hasn’t changed. The source code of the S1 app and the S2 app should be enough to get the functionality in the new app. 
 

for me it means I won’t buy new sonos equip anytime soon. Well done Sonos…not

To my knowledge it is Mixcloud that should use the Sonos api, not the other way around, see https://docs.sonos.com/docs/smapi. That’s the way Sonos works. Did you contact Mixcloud?

Ummm.. don’t think it’s mixcloud at all. I use the SonoPhone and SonoPad app for my Sonos. Have to have the crappy Sonos app to do so. However,,,, mixcloud , SoundCloud, and all my other music services work flawlessly with these 3rd party apps. Nor do I have to do the Sonos app updates.  When users using the Sonos app couldn’t get the SoundCloud or mixcloud to work.. it worked and still does for me. Think it falls on Sonos. 

I’m not into the technical intricacies of SMAPI, but I have noticed a couple of music services stopping around the time the new app/software was introduced. Maybe the new software, relying heavier on cloud services, takes an extra step for content providers to make? The non-Sonos apps do not use thes cloud services, so would still work. Then this could be caused by Sonos’ choices, but be the responsibility of the content provider to solve?