So, I’ve had my Sonos system for a few years and recently had nothing but problems with it. On my partners phone all three of our devices show up (Sony) and on my iPhone I only get 2 of our three devices. Both logged into the same system. 
 

Ive restarted all devices, disconnected them from the system and rejoined them but it still won’t appear on my controller. 
 

the missing speaker works fine on his device but I can’t even see it when I search for new devices.

two Sonos One devices appear on my phone but not my PLAY:3

any ideas? Fed up of the unpredictability with the system.