Thanks, your post was helpful as it gave me the confidence to push the update button
After I migrated, to HA 22.8, I discovered the UI input box for medi_player.join was enhanced for grouping and the new process seamlessly joined the sonos entities. The code was identical to your example, and all was good with this part of the HA 22.8 update.
Please consider marking my post above with the Solution tag. It will automatically place a check-mark next to the topic’s title which signals to other users that this topic has been resolved. This helps users find answers to similar questions.
I am new to Homeassistant and have really enjoyed looking at the forums.
I have been using SmartThings and my Sonos system was recognised and it works.
Unfortunately in Home Assistant, when I “migrated” devices from SmartThings, are listed as a device but not recognised when I added the Sonos integration.