Working SONOS speaker not visible in Homey. Why?

Hi. All my SONOS speakers are visible in Homey except for one, a 1st gen SONOS Play:3 speaker.

Homey Pro 2019
SONOS app v6.2.1
When I use SONOS, I use the S1 app (shouldn’t matter)

I’ve tried “Hey Google, synchronize my devices”, “Reconnect (SONOS) Account” in Google Home and restarted the SONOS app in Homey, but this stubborn SONOS speaker won’t appear.

Anyone have an idea why not?