Hi @roger corke thanks and welcome to the Sonos Community. We appreciate you raising this to us. I will be asking a few questions in order for me to fully understand the concern. Please answer these questions:

• When did it start happening?
• What device are you using to navigate the Sonos App?
• Have you tried using a different device to navigate the Sonos App to check if you are also getting the same error?

Kindly submit a diagnostic also in order for us to check your system. Let us know if you need further concerns. Thanks! 

Apologies for taking so long to reply - I misse dthe email saying you had responded.

It started when I moved over from the old Sonos app to Sonos S1 and it’s happened ever since. It only happened on my Mac - there’s not glitch screen on my iphone, iPad or my Sonos controller. I spoke tdo Sonos, who said I should move the daily update of my music library to a different time (from 2am to 12 noon, in my case). That jus tmeantd I got the same glitch screen in the middle of the day rather than first thing in the morning when I opened up my Mac