Leviton wall dimmer "disappears" from Devices

Twice in the last few months, one of my switches has just disappeared from ST. I didn’t remove it, it’s just gone. I have about 100 devices, this one has done this twice now. I assumed I did something to screw it up last time, but it’s happened again.

Is it possible that the system can drop devices for no reason? Is it possible that I did an exclusion and it somehow excluded without being toggled?

It seemed that way to me a couple of times. Last occurrence was when I was away from home & “lost” a hard-wired wall switch. I would have tried power-cycling the hub, the switch, and so on. But I was 1700 miles away. Instead, I asked our daughter to turn off the entire house at the main breaker, then switch it back “on” ten seconds later.

That worked: all devices back & functioning correctly. YMMV, of course…

I’ll try thst, but I’m very skeptical. I logged into the dev panel and it wasn’t there either.

I pulled power and batteries from the hub for a few minutes, and rebooted.

The device did not reappear- I didn’t expect that it would, considering it was gone from the Dev panel.

A few minutes ago I was in another room, and the light suddenly turned off, and the Leviton Dimmer quickly flashed red-orange a few times.

So I logged into ST to see what (if any) notification it had issued, and… that dimmer wasn’t listed either. Logged into theDev portal and… GONE.

Both are Leviton DZ6HD-1BZ. I have about 10 of these in the house now. I spent $$ last year and bought several different devices to see which one was the best, and these won. Now I am wondering if I made the right call.

I had to exclude both switches before adding them back. Of course now I have to update a couple smart apps.

But IS THERE ANY LOGGING?! How can devices just disappear?! Is this an ST Bug or a problem with the devices?