Set up your HomePod, HomePod mini, Apple TV, or iPad as a home hub - Apple Support (CA)
According to the Apple Support..you need a 4K AppleTV.. I had a 3rd Generation HD AppleTV so I thought ...
"You must set up a home hub to add Matter accessories to the Home app.
Thread-enabled Matter accessories require a Thread-enabled home hub,
such as HomePod mini or Apple TV 4K (3rd generation) Wi-Fi + Ethernet,
or a supported third-party border router."
.. and so with my stupid desperation, I went and got myself the Latest AppleTV /4K 128Gb WiFi + Ethernet ...!
The end result is STILL THE SAME problem ! No Go ! My shared users still not receiving any of my INVITATIONS, after sending several the Home App Invitations ! This is getting ridiculous ...
C'mon Apple Support !!! you need to acknowledge the problem or tell us whether the problem is in your HomeApp software or your iCloud Servers !? so we don't have to keep banging our heads, trying to figure out to resolve this Home App's Invitation Issues ! Give us the Fix , man !