*can choose not to eat back the exercise calories
There is already a deficit built into your budget so that you will lose weight without doing exercise. The deficit is calculated using your target weight, current weight and the date you want to reach target. As you exercise you burn more calories so your budget increases so that your overall calorie deficit stays the same and keeps you on track for your target. Obviously you can not eat back the extra calories you are allowed by doing exercise but you then risk slowing your metabolism down and your body going into starvation mode due to not consuming the calories it needs. Hope that makes sense.
That's happening to me too, and I don't think it should do that