Releasing Sonos Speakers after Roon Playback

Running Roon Server on a Mac Mini. I use Roon to play audio to my grouped Sonos speakers (2 x Play:5, stereo grouped, a Play:3 and a Play:1 - Gen 1). Works great.

Then, I stop playback and go back to the Sonos app to play something. The paired Play:5 speakers work fine, but nothing plays from the :3 and the :1. I rebooted the smaller speakers, regrouped and everything went back to normal.

Is Roon “hanging on” to the Sonos speakers and blocking Sonos from sending audio, after playback is paused on Roon? FWIW, I did switch playback to another Roon endpoint, but nothing helped (other than power cycling the Sonos speakers).

The use case: I like to use Roon, but my wife and daughter use the Sonos app or Spotify Connect to play music throughout the house, so I need to support both methods (not at the same time, of course).