My wife and I both have Forerunner 235's.
There is a difference in Heart Rate readings between these 2 devices of 20-30 BPM.
Due to this when walking her HR is not recording in any zone and therefore showing as not burning calories.
I checked my HR using my 235 and it said 80, I then swapped to hers and it showed early 40's - this seems to be too extreme a difference.
Should I put in a support call for this, or could it be a setting on the watch?