GE Z wave dimmer trouble

I have about 40 GE Z wave dimmers model 12724 spread around the house, all but two are working great.

One cannot be seen by the hub even if the hub is 6’ away (moved the hub directly in front of these two to test), I have never been able to add this device.

The second one was initially added, but almost immediately stopped working. Now I cannot remove, exclude, or communicate with this device at all.

Both work manually (on/off and dim). Both are in same location as other GE Z wave dimmers that are talking to the hub and working well.

Is it possible that the radios in these two devices have failed?

Any tips on removing a device that fails the remove and exclude procedures?

Thanks, Dave

You might want to check out here:

It could be related.