HomeKit accessories stop working when AppleTV is the Home Hub

HomeKit is a black box full of swamp voodoo, with no troubleshooting tools other than “try rebooting everything” and “delete the entire home and start over.” That's like Windows 95 redux. Some people find that things work better with a hard-wired ATV as the active hub, for others only the HomePod makes it all function, for some it works every time, for some it just never works. It’s so inconsistent as to be incorrigible. Worse, HomeKit takes a relatively long time — at least several minutes, if not hours or days — to propagate configuration changes. It’s the worst smart-home system out there, except for all the others.

Each problem case is different. In my config, if I enable my ATV4K as a hub, it gets promoted to primary since it's hard-wired, and half my accessories go unresponsive. I have to disable it, and let my HomePod Mini be the only active hub, which is a pain because I need the additional Bluetooth coverage that the ATV provides for certain accessories. Resetting/reconfiguring the ATV didn't help. Updating everything to the latest OS (currently 16.1) didn't fix it. I even went through the "delete the entire home" process a couple years ago, and I'm not doing that again. That's not troubleshooting, that's shot-in-the-dark guessing.

We need to be able to clear caches, force HomeKit data synchronization, trace accessory communications, view log files on the hub(s), verify mDNS functionality, that sort of thing. When submitting this question, though, I notice that there's no HomeKit category anywhere. Doesn't exist. When is Apple going to treat HomeKit as a real product, and give us some good diagnostic tools for it?