I have this bug in the latest (October update 80.10.06) of the android app.

If I select “Add to Queue” for a single track from my Music Library, then the queue is no longer accessible from the “playing” window.  I get the error message “Unable to load.  Please Try Again”.

Selecting “Add to Queue” for an album seems to work correctly.  Also for a single track/item for other services (e.g. Soundcloud, Amazon Music are ok).

This has been reported to Sonos.

Other points to note.

1. The track IS added to the end of the queue.  But I can only view it in my PC Windows Sonos app.  So the queue is ok, just no longer viewable or accessible in the Android app.
2. The Queue is no longer visible or editable on the android app.  You cannot clear it.  The only work around is to add something else to the Queue using the “Replace” option.  This “resets” the queue.
3. If you add a single track to the existing queue in the windows app, the updated queue is still visible on the android app.  

Tried all the usual… Sonos system updated and rebooted, Wi-fi router rebooted, reset android sonos app and cleared cache and data, even refreshed/updated my Music Library.