Don't recall but I find stuff missing from the app fairly often. I close and reopen it and usually things go back to what they should be.

Couple times they didn't and a force-close got me back working.

If it bothers you enough submit a diagnostic and call it into Sonos support as a bug. More reports usually means a higher priority. Forum posts may or may not make a difference unless there are a lot of users posting.

Make sure all devices are running the same firmware version.

https://github.com/amp64/sonosbugtracker/issues/4