I got 3 HomePod minis around my apartment and 1 Apple TV 4K as home bridges. In addition, we have 2 iPhones, 1 MacBook, 1 Mac mini, 2 iPads (air and mini) as well as 2 smart light bulbs.
Okay guys, the following worked for me:
Turn off (!) every single device you have and uninstall the home app from every device as well but your own iPhone (or whoever is the owner of the home). If it helps, unplug everything as well. Turn off iPhones and iPads with the hard reset (up button, down button, hold power button until you see the logo on black screen)
Then, turn on the owner’s iPhone only.
Then the “main” home bridge you have. If you have several like me, the devices make it up on their own, but my Apple TV was always “connected”, the HomePod Minos were always on “standby”. So in my case I turned on the Apple TV first. It doesn’t matter which device is closer to the WiFi router.
After your iPhone and the Apple TV (or HomePod if applicable) are completely ready, try to delete the other user(s).
This hasn’t worked for me the days before. But now it did. Everyone got removed and I was the only one remaining as the home’s owner.
Then turn on the other person’s iPhone. If this one is ready and the home app is re-installed, open it and click on everything it asks you to.
All done? Good. Re-invite this person.
It should work at this point.
The other person accepts now and configures everything the app asks.
Don’t worry, if voice recognition doesn’t work: you need a HomePod turned on for that as the Apple TV hasn’t got a mic.
Now turn on every other HomePod one by one. Slowly. Then the smart devices like light bulbs etc.
At last, turn on voice recognition etc. which should work now.
Also, making someone else an admin should work now.
Share this, if it worked. Make others happy.
Have a nice weekend and merry Christmas to you all!