The next time it occurs, submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

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.

Just waited for the error to happen again and it just has, so I have sent diagnostic to Sonos, yo see what they say. Thanks for the info

Make sure you call in, as they don’t normally look at diagnostics sent in unless prompted to. Too many ‘false submissions’, I suspect. 

Talked to support 5mins after sending Diags and gave no. Went through all the usual I.e. make sure app has location and BT permissions   restart Sonos speaker etc. After a load of back and forth, they seemed to dismiss dials and nothing seemed to help. I told them that the issue was OK on iPad. Queue was loaded no issues. They said they would look into it and come back. That was last Saturday. 

Will check with them soon but will use iPad for now.

Got so tired of this issue. Decided to look online after updating to latest app and device firmware. Same complaints unfortunately. So quick test on one speaker. Queue shows up. Added lots to Queue, still showing up. Back to existing grouping of speakers, Queue unable to load. 

Tried separating all speaker groupings and cleared all queues. Seems to be working now! Still will not open Queue to current playing track though.