Speakers Continuously Disappearing

This week 3 of my 12 or so Sonos speakers have started disappearing. I have done the usual turn off, then on, then restart the router.

Here’s the weird thing - when I am using the “find missing speakers” function on my app, and I restart the router, the app “finds” the speakers every time. HOWEVER, on our other devices (other iPhones, other iPads) the speakers are still missing. Even when I am actually playing music on these speakers, the other devices cannot find those same speakers. I have tried restarting the apps, restarting the devices, deleting the Sonos app and reinstalling it, and same result every time. If I run the “find missing speakers” function on another device, then that device will “find” the missing speakers, but then they will disappear from the device I previously used to “find” those same speakers. In other words, if I jump through the “restart speaker” and “restart router” hoops, only one device at a time will “find” these missing speakers. Also of note - the “missing” speakers are in the same room as other speakers and devices that have no problem connecting to Wifi. Two of the “missing” speakers are within 15 feet of a Wi-Fi access point, but again Wifi does not appear to be the issue since I can actually play the speakers that other devices running the Sonos app cannot “find.”

I ran a diagnostic, with confirmation 1200119012.

My Google Home app has no problem locating the speakers that the Sonos app cannot find, and again these same speakers are actually streaming music while the other devices cannot find them.

I don’t get it.