So I was having a nightmare with the sonos app after adding Roam. Literally zero speakers showing up - no playbar, Play 1’s or Roam.
Did all the usual - unplugged/replugged in speakers, switched router off and on, etc. Nothing worked. However, noticed my wife was having no issues - exact same model of phone and version of the app.
this led me to my own device so I went into the setting and did a reset on the network settings, rejoined the WiFi network and now everything is as it should be.
thought it useful to share as its good when these rabbit holes actually have a simple fix!