Everything is up to date, firmware 16.3, new IOS apps on all three of my iPads. What is happening is, you have a queue in a room, that was playing, but now paused, you go to another IOS device (iPad or iPhone) and when you go to that room or speaker, the queue disappears and says “no music”. I watched it in real time by bringing up my Windows Controller app and when using one of iPads to change rooms, the current queue gets totally removed. This is with the newest app dated 7/17 even though it was released yesterday, 7/22. 

Moderator edit: changed all “playlist” to “queue” for clarity.