You’re not crazy. I too thought we were getting close there for a while. Just before I left on vacation in July, I was able to get 5 of my 7 Sonos zones playing fairly reliably. That may have just been a fluke, however, as for the past month I’ve had consistent dropouts again.
important to note: the dropouts are no longer “Transport Lost Control” error messages. Roon now shows all my Sonos zones grouped and remaining together. It just very rarely wants to play to more than 1 or 2 of them at any time. The others will all randomly pop in and out, stutter and die, or just never pick up the stream at all.
Literally as I type this, there is only 1 of 7 grouped zones playing. I find if I spam the pause the Play/Pause button, I can shock the network in picking up an extra zone or 2 occasionally.
I figure the team is probably busy polishing the latest round of features they’re working on, so I’ve been a little more hush about this issue in recent weeks, but my better half loves to remind me how these issues never existed before we switched to Roon, so I’m eager to get this Sonos integration sorted out once and for all.