Pairing Konke temp and humidity sensor

Hi, I’m trying to pair the Konke temp and humidity sensor (most likely this one: https://www.zigbee2mqtt.io/devices/2AJZ4KPFT.html) does anybody has experience with this sensor?
As I have a smoke detector, which I needed to manually add, and motion sensors which directly could join, the temp and humidity sensor does not seem to show any attempt to join. The batteries are full, I have two temp and humidity sensor (so it is unlikely, not impossible, both of them are broke) and I’ve tried a similar approach to the motion sensors of Konke, which is: remove the power source for 30 seconds then re-insert the battery again.

The sensors themselves do not have any (?) buttons to force joining, such as what the Tradfri of Ikea or the Konke smoke detector do offer.

I’m using a flashed cc2431 on a Raspberry. I have set the channels to be either 15 or 20 (as recommended and needed for the other Konke sensors too). The other sensors just mentioned had no problems showing up. However the temp humidity seems to remain totally quite. Any ideas to proceed?

Kind regards.