After ±20 re-pair attempts I still had no success with pairing. This was a clue as I had a significant higher success rate before (although the module was added as a generic Zigbee device). My assumption was it was connecting but getting stuck on something. So I ended up clearing my endpoints key in driver.compose.js. Re-paired and it got paired on the first attempt! So the content of my endpoints key was invalid all the time.
Based on this thread Zigbee Thermostat cluster undefined I was able to log the current temperature. Progress! Now I can finally start developing the app. Thanks again @robertklep !
