Volume bug craziness went away immediately for me when I un-plugged the Roam from a wired charger. So I’ve isolated it to when the Roam is connected to a non official power adaptor. It destabilized the entire Sonos network and introduced bizarre App volume slider behavior and grouped volume bugs.
I wonder how many Roam issues are linked to the cost cutting decision not to include a simple power adapter? If related Sonos has risked a big reputation hit, alienating new users to the brand and countless returns all to save a couple bucks on an adapter. Considering how picky the Roam is with power adapter needs this doesn’t seem like a good call.
All is good again in my Sonos world, hope this helps someone.