I have a turntable connected to Port (named Turntable) and I have an arc soundbar grouped with the Port.  My turntable sounds through the Arc just fine. Problem is I use the Arc also for TV sound and to stream music in my master bedroom (the Arc is named master bedroom).  When i ask my voice assistant (Sonos or Alexa) to play music on “master bedroom” I hear nothing. When I open the app I see the music playing on “Turntable” and have to manually group it again with “Master Bedroom.”  I’ve tried turning the Arc setting to “ungroup on autoplay” both on and off. Doesn’t seem to affect the issue I’m having at all.  I had used the Port and Arc grouped previously with no issue. My system hasn’t changed, though the app had been upgraded and Sonos Voice added since I setup my Port and Arc. I’m at my wit’s end with this and tired of having to manually control these speakers. 

Sorry I don’t have any solutions just the same problem. I have an Arc and a Sonos One and I can group them and they will both play, but give it a few days and they always become ungrouped. All you can find online says to turn off “ungroup on autoplay” and that my wifi signal could be bad. I have checked both: I think Sonos software is full of bugs and this is pretty far down on the list :/