What app are you using?

Desktop app for Mac.  

TBH I’m just happy if I hear music when I tap play.

The Mac app hasn’t been updated for years. I’d try a couple of things. First, try the rescan from a mobile device, and see if it completes, or freezes up. If it does freeze up, I’d be tempted to reboot all my Sonos devices, to force them to reload their firmware. I’d also probably delete the Mac app from my machine, and download and install a new copy, making sure to ‘Connect to existing system’ when prompted. 

If all that fails to change anything, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, they get sensitive about GDPR.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.