I've given up on trying to make my once working Apple TV Home Hub respond again. So I logged the apple tv out of the appropriate iCloud account and decided I would make my iPad the HomeKit hub. Much to my chagrin, there does not seem to be a "Make iPod Home hub" option showing up under the iPad/Settings->Home (where all the instructions tell me to go an enable the iPad as the hub)
Per instructions, two-factor authentication, keychain, and Home are all enabled under the iPad/Settings//iCloud settings.
Suggestions are welcomed. Being unable to share lighting control with other household members is causing a great deal of irritation.