Unable to pair Monoprice ZWave Plus Motion Sensor

I know this question has been beaten to death a bit, but I haven’t found a reliable solution anywhere, so I’m posting anew.
I recently purchased two of the ZWave Plus motion sensors from Monoprice.
Out of the box I had trouble pairing both of them, but eventually one got paired.

The other still will not pair.
I’ve removed the cover, set ST Pairing mode, inserted the battery, and held the sensor very close to the hub. I’ve also inserted a pin to push the program button in the back. The LED flashes on/off repeatedly, but the sensor is not detected by my hub. I’ve tried hitting the program button once, hitting it repeatedly, holding it, holding then tapping, etc… The LED flashes, but ST doesn’t pick it up.

I’ve also tried the same procedures with my SmartThings system in Exclusion mode, but it doesn’t detect the sensor in Exclusion mode, either.

And I’ve installed RBoy’s device handler, which is working well for the other sensor.

Any advice? Ideas?

You may be running into a problem that SmartThings is currently listing which is trouble adding z-wave devices although you might want to contact support since it was a couple of days ago. Or, it’s possible that you have a defective sensor.
See here: https://status.smartthings.com/

“Investigating - Some users are currently experiencing errors when trying to add and remove devices via the mobile app and the IDE. Additionally, Z-Wave Utilities from the IDE, such as Exclude and Repair Z-Wave network, may be non-functional at this time. These utilities will still work via the SmartThings mobile app. We have identified the root cause and are working towards a resolution.”