I recently bought two of the Monoprice Z-Wave Door and Window Sensors and was able to pair them just fine, however they only correctly report their status for a few hours and then begin showing up as “unavailable” in the Smartthings app. It seems that whenever the sensor’s status changes (either by opening the window or removing the sensor’s cover) it will correctly show up as open/closed for a few more hours before becoming unavailable again. What can I do to make these sensors behave like my other door/window sensors (two Smartthings brand, five Iris) which show their status all the time?
Sounds like they were not fully included properly. Use the replace option in the ST app to reset and reconnect them to the hub.
I re-paired the sensor per your instructions, but I also changed the device type in the Smartthings online control panel. I originally had it set to “Z-Wave Door/Window Sensor” and changed it to “Z-Wave PLUS Door/Window Sensor.” Either or both of these tweaks fixed the issue for me.