Hello ​@Nick F, welcome to the Sonos Community!

I’m sorry to hear about your experience with the Sonos App and your Sonos system.

Since you’ve done all the basic troubleshooting steps I would have suggested, have you reached out via phone to our Support team as you mentioned?

That would be the best course of action. Feel free to reply here with the outcome of your interaction and I hope you get back to enjoying your Sonos system soon.

Are any of the players wired to the network? If not, try wiring one or more players to the network. Don’t Factory Reset anything without further consult.

I have something similar, no content showing on the app, however i do have audio, Arc Ultra. 
 

I have 1 Era 300 and 1 Ultra. 
 

In the app the current selected source, yellow tick, is not the Ultra, even though the Ultra is active/playing. 
 

Also, I originally had the Era as Bedroom, added the Arc to Bedtoom, assuming you can have 2 products labeled as 1 room, but it automatically put the Arc in Bedroom 2, so I have Bedroom and Bedroom 2. 
 

Currently Bedroom has the yellow tick and seems inactive according to the app

Bedroom 2 has no yellow tick but says tv hdmi and the little waveform animated icon. 
 

Somethings not right there. 
 

Signed out of app, resetup Arc, uninstalled/reinstalled app, no change. 
 

Not the end of the world but annoying 

edit: When i factory reset Arc and added it back in Sonos app i chose to re add the existing products back, maybe I should of not done that and started totally fresh and removed and re added Era300 as well. 
 

will see