When I added mine I found it odd how I got mine to work.
Like you ST treated it as an unknown device/thing and put it in the list.
I selected it and added it in the App. Then went over to the IDE and changed the devicetype to Centralite Keypad.
At first the keypad didn’t seem to work properly. It wasn’t changing the SHM status.
If memory serves I believe I hit the Off button and waited then the Partial button and finally the On button.
Still it wasn’t working. I believe I put in a code like 1111 - On and still nothing.
I did notice the pad started behaving differently after doing this.
So like you I went to the App, selected the device and Clicked the Configure Button still nothing. Then I clicked the Refresh button.
This is the part I am not certain about but I tried either pushing the Off/Partial/On buttons then entering a code like 1111-On.
I may have even rebooted the ST Hub. I believe I went back to the App and clicked Configure again and for some reason it started showing me Temperature and Battery Life in the App.
I figured Eureka and then tried the Keypad again and this time it changed the SHM status.
Not entirely certain why it behaved this way. So far mine has stayed paired and has been working fine.
I did not perform the Factory Reset on mine. I never had to. Not that this should matter.
Seems to me if it is working for you then later loosing connectivity you may have a hardware issue with the Keypad itself. Or weak batteries. I am only guessing.