What is the temporary fix? Knowing that might help identify a longer-term solution. 

Their 'fix' was to start playing something in it's own app, BBC Sounds for example, and then transfer output to the Sonos speakers. That works until I reset the iPad/iPhone/Sonos is power cycled then I'm back to where I started.

Have you created and saved the group, and then tried playing to that named group? 

As I understand it, when grouping dynamically, there’s a “master” speaker. With dynamic grouping, whichever speaker the others are grouped to is the master. What it’s playing should come from the other speakers too. But if the music you want is playing to the Kitchen and you group Kitchen to Lounge you get what’s playing to the Lounge - nothing if it’s not playing anything.  

You have all your devices well configurated in the app Alexa, and also, you have activated both assistant (Alexa and Sonos Voice Control)(Only in speakers with microphone) I think with Alexa you request it and the Sonos assistant makes it.

Hi ​@JadesFire 

Welcome to the Sonos Community!

Sorry to hear about this issue you are having with Alexa not playing to a saved Alexa group properly.

You mention a speaker pair in the Kitchen, then an Alexa group named “Kitchen” - please be aware that if you name an Alexa group to have the same name as a Sonos room, things will not go according to plan. Please use an alternative name for the group such as “Downstairs” or “usual speakers” or similar.

I hope this helps.

​@Corry P I'll check that, I suspect there will be duplicates. Thanks.

I have always had a problem with groups for SONOS both directly in the SONOS app and Alexa not working correctly.  If it is set up as a group I need to shut down and add the speakers individually.  I gave up on grouping in Alexa several years ago and haven’t tried recently.  It is still a continuing problem with SONOS.  Sometimes it works and sometimes I need to shut down and restart everything.  I have pretty much giving up on groups unless the speakers support AirPlay directly (not as a group) and I can using airplay.