The sleep timer appears to be back in the 5 June update, however it only appears for Services such as Spotify and Sonos Radio. It is not working for the local Music Library.
When will this be fixed please Sonos?

I also found the local music library doesn’t have the sleep timer function with this new update.

Same for me. The 3 dots at the bottom right of the playing room screen (where I expect the sleep timer will eventually make its triumphant return) are grayed out. For now, my workaround is to create playlists that are only as long as I want music to keep playing at night.

I have a local.music library on s NAS drive.  I do  have sleep timer when this is the source 

Interesting.  Did you create this library recently or was it pre existing before the app upgrade?  I have the same, my files are on a NAS

Pre existed before the spo upgrade

I am a 20 year Sonos devotee, upgraded my system regularly, but find it outrageous that the new app excludes the timer function. We always play classical music going to be but there is no way to stop it with my iPhone (asking the phone to stop at a set time does not seem to work on the Sonos App even though it does for all my other music apps). HOW CAN I REVERT TO THE OLD APP ON ALL MY MAC DEVICES???

I have the new app on both Android phone and iOS iPad.   I can now set the sleep timer on both devices.   If you cannot set the timer on your iPhone, are you sure that you are on latest update?

To double check (on the mini iPad) go to settings/iPad storage/sonos   On mine I see that the version is 80.02.04.   If yours is not this one, offload and then reactivate

I have the latest version of the Android app, version 80.03.03 and I cannot find the sleep timer when playing music from Spotify. The three dots menu shows me only this:

Are there some news about that ?

Still have the same problem here after the different Sonos updates, sleep timer only available for services, not for my local library. Really annoying.

I don't even have it for services

Just came back to say that sleep timer is back for my local library thanks to the update that occurred today (July 1st). Thanks.

I don't know why but I still don't see the sleep timer in version 80.04.04 on Android when playing from Spotify (or Soundcloud). Anyone else on Android have this problem?

It’s back! Happy to report the sleep timer for local content is back in build 80.04.04 of the iOS app, which was released July 1.

On 20 July 24 I found sleep timer accidentally  on the new app. It was buried deeply and against a single system component but now I can’t relocate it. It is not intuitively found.

typical bureaucratic CMA manoeuvre - make an unannounced correction and months later proclaim “nothing to see here”. More transparency required Sonos - if you can emails announcing a new app and force feed the new app you can sure as hell notify all Sonos users of the correction and how to find it!

In the iOS app, when you have music loaded and ready to play or playing in the queue for a particular device or room, click on that device or room in “Your System” to expand it. You should see three dots in the lower right corner of the screen next to the device name. Click on the three dots and that should bring up the sleep timer. Not easy to find I’ll grant you, but it is there now.

Finally the sleep timer is back on Android on 80.04.05 for services like Spotify (I haven't tested local library)