It is correct behavior of the application. It defaults to two activities - sleep and rest. This is because you burn the calories all day long, even when you sleep and rest. To add exercise, you need to replace some of the sleep or rest time with actual exercise. You cannot delete sleep or rest, just replace with X min of other activities. It is general consensus on the forum that replacing rest with activities like driving or desk work (i.e. low impact activities) will result in FS overestimating your calorie needs. So it makes sense to only track actual exercise or work that makes you burn a lot of calories.
The first thing you lose on a diet is your sense of humor. ~ Author Unknown
It doesn’t matter what diet you follow… What matters is what makes you follow your diet. ~ Tom Venuto