I just updated the SONOS V2 app to V14.0 Build 67125130 on an iPhone 8 and iPhone 8 Plus and they both will randomly not show the playlist that have been previously created. If we force close the SONOS V2 app then it will some time show the playlist. Both iPhones have been updated to iOS 15.3 and have been rebooted numerous times.
All music has been ripped to the FLAC format and is stored on a SYNOLOGY DS1821+ NAS running the latest DSM 7.x operating system.