A New Linear GD00Z Problem?

At the risk of beating a beaten and long deceased horse, here goes.

I have two Linear GD000Z garage doors (z-wave). One of them, ironically the one that is closer to my hub, has no problem pairing in secure mode and no problem opening, closing, and tracking state..... but then it magically stops responding to any commands after a few days. I can open and close my garage the old-fashioned way, so that's not the problem. The unit further from the hub has never had any problem. I have multiple mains-powered zwave devices close by, so mesh quality should be good. I usually remove the device and then re-include. I'm getting tired of getting the ladder out every few days for this darn thing.

Oh, and yes, I've replaced the battery in the tilt sensor too. And yes the device includes in secure mode so that's not it either.

Any way to diagnose whether I have a defective product? Or if it's a mesh problem? Or something else? I have a second HE hub that I just received. While I have other plans for it, I was thinking about setting it up, adding the garage door to it, and see if it makes a diff.

Thoughts from you brilliant people? Go....