I had same issue, then noticed that the display shows a beating heart icon, but it also has a solid ring around it. The ring extends around the heart to display what band you are in: if ring is from 6' oclock to 9, oclock, its 'out of band'; from 10 to 12, its Fat Burn; from 1 to 3, its Cardio; and from 4 to complete ring, its Peak.
It seems to work pretty well, as the extent of the ring is much easier to see when outside than a number would be.
