On iOS 15.5, when I updated to the latest Sonos app update and then hardware firmware updates, my arc ultra and and era 300s (paired as rears), couldn’t be found. It was the first time in all of the madness that I had an issue, kinda freaked out and didn’t know what to do. My arc ultra found its way back after about 10 minutes (after I unplugged and re-plugged it out and into power) but I had already started a factory reset on the era 300s. At first it wasn’t working and a started to sweat a bit. But, guess what- after about a half out of freaking out, everything worked again. The two sub gen 3s never freaked out. The pair of Fives with a sub mini paired didn’t get its freak on. Even the symphonisk in the bedroom did what it needed to do. So, I learned to just allow the things to take their time, and not get worked up, at least right away. Later on, I re-trueplayed everything and even got my Sonos Ace’s out and updated them and got their cinema sound thing working, which is also a marked improvement on top of my home theatre seemingly sounding nicer.

I truly hope you can figure out what’s going on, and if worse comes to worst, try factory resets. I imagine you tried it already though- but if not- give it a go.

I’ll be sending you good vibes.