Have similar issue while connect 1-wire sensors to pins 4 (power) and 5 (data) for low energy sensor. Looks like at least pin 5 used internally (as LED ?) by MySensors and broke 1-wire i/o. After moving 1-wire "data" pin to "A1" and hardwire "power" pin to "VCC" I have no issues with DS18B20. But about 3.5uA per sensor more in sleep (11-12uA instead of 4.7). BTW: still have issue with node registration and/or other connection issues - after approx. 2 days node whan't to send data to gateway... Will debug later. PS: MySensors v2.0 from Arduino Lib manager, Arduino Pro Mini 3.3V@8MHz@4.1VLiPo

@pkriek If you can stick a light sensitive resistor onto that light you could measure when the light goes on and then do something (like send a message to domoticz). I'm also looking for a way to count the number of times a door opens (similar problem), no solution on Domoticz yet, still looking.