The forum suggested I send a message directly to you.
I tried to add the device, again, using the Insteon Panel. The dialog came up asking for the address (which I’m never sure if I should give as 5021f0 or 5021F0 or 50.21.F0). After a while of no response, I went to the device and pressed the set button (not long press, just press and release). Nothing happened in the dialog. So I tried pressing the button again. I definitely heard it make a little chirp. But still no device.
And, of course, while I was typing this, it said the device was added. Unfortunately, I can’t see the dialog right now to see what it said. I’m assuming that it is still not going to work, but I DID reboot the hub, in case that makes a difference.