I’m afraid this is not a matter of deCONZ support, as it is running perfectly fine. Please also note that quite a number of people seem to share your experience which is not deCONZ exclusive, but happens frequently with z2m, zha and others.
I’ve checked the code once again and what’s transferred via zigbee since I wasn’t too sure if I verified the value which is being used to get the current setting from is really adequate, but it is. Having reread the posts now perfectly makes sense, also, that it works only once, as you set a lower value.
Now why doesn’t it work?
The answer is pretty simple: you haven’t waken up the device by pressing the button on the back 
And just to be clear, this is specific to the device and mandatory as that press enables it to receive anything