So your Sonos app sees it but ST doesn’t.
Hey, did you try to use a SSDP explorer?
I recently lost a D-link camera and despite the D-link camera was working with their app, ST wasn’t able to find it.
So I downloaded a ssdp discovery app on my laptop (I used windows store “SSDP scanner”) to check if it was able to find the camera and, same: the camera wasn’t found.
So of course, if the device doesn’t publish its capability profile, there is no way ST can find it.
So check it. With your Sonos, you should fine a lot of Sonos capabilities. If you don’t find any, then try what I did.
It sounds weird, but I went to my router, removed the static IP assignment I add on my camera to the IP address, saved, then tried again: miracle, the capabilities were back in the SSDP tool and ST was able to find the camera back too. Then I reassigned the same IP address as a static and it works well since.
I have no idea what went wrong and in what this IP address would have been kind of half working.
My router is an Asus, just in case.