That seems odd. Have you set limits in the Sonos controller? What source are you playing on the Era 300? Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it?

My sosnos doesmt have a controller.

 and I haven’t yet reached out to support 

If you don’t have a controller, how did you install the system, or even update it?

I’d definitely be calling support.

I was using The beta app at the time. That was about two years ago

I’d assume / hope that beta was complete, and closed. Have you migrated to a new controller? What did Support say, when you called in? 

Add this exact same problem and I called them and it was because I had my speaker not sitting Correctly. I literally had it upside down, and I am sharing that because somebody needs to learn from my idiocy lol. Working like a charm now