Best answer by melvimbe
You might want to repeat the issue and submit a diagnostic within 10 minutes afterwards. Post it here. That might give a Sonos rep something to look at. Calling or using twitter/fb maybe faster.
You might want to take a look at the Alexa groups again. I think a recent Alexa update may be automatically creating groups for newly added Alexa devices. If that's happening, and the names of your devices are getting croossed somehow, maybe that explains what you're seeing?