The good news is, it seems Google engineers are trying to correct the buggy Google Home "Speaker Groups" feature. It now works correctly more often than previously.
THE RESOLVE: This however is only because I discovered it had somehow created more than a dozen copies of my "Whole House" speaker group. I deleted all of them, rebooted the phone, unplugged all speaker devices, rebooted the network, plugged speaker devices back in, now having zero speaker groups I recreated the default "Whole House" speaker group and all has been working well for the past couple of days. So I keep checking to see if mystery speaker groups start showing up again, but so far so good, no new ones have been appearing, and all continues to work correctly.
If someone out there is reading this and still has the "Can't find "Whole House" (or custom named speaker group), try what I did, as it may likely resolve the issue. Google Engineers and tech support staff should be alerted of this too.
Thanks for reading
