Sonos doesn’t support Dolby Atmos music on TIDAL from the mobile TIDAL app or from the Sonos app. You need to use the TIDAL app from a TV or streaming device that supports Dolby Atmos. Read more here:

https://www.dolby.com/experience/tidal/

Or just stream Dolby Atmos music from Apple Music or Amazon Music Unlimited directly from the Sonos app.

Just to get the right Sonos lingo in here: when you've set up your system in the right way, in Sonos terms they form a "room". Two "rooms” can be “grouped". So you should be streaming Tidal to the home cinema "room". 

So Sonos the streaming speakers that I bought to stream Atmos doesn't stream Atmos. Amazon music is not available in my country sadly. So I guess I have to give up on Tidal and switch to apple even though I don't own anything by apple.  Not very good especially as Tidal is supported by Sonos 

Why in the world are you blaming Sonos?  Atmos Music is obviously supported on Sonos,;Amazon and Apple both supply Atmos Music streams which Sonos is able to play.  Common sense says the missing element is Tidal, not Sonos.  It’s like blaming your color capable TV because a station is still only showing in black and white. 

You are correct. I've switched to apple music and cancelled my tidal sub. Thanks