Hi Michael,
Yes, today they disappeared completely on two different moments. Suddenly I only saw the Roon bridges and other endpoints, but not a single Sonos speaker. After a while, they all returned.
It was each time all sonosspeakers gone, and all sonosspeakers back. Not some of them.
It was the first time I noticed that. So if there is a bug that’s about sonosspeakers completely dissapearing in Roon, I can confirm this is also the case in a wifi-only setup.