Map marker always faces East while using boat.

When I travel using a boat, my map marker only faces east when I am looking straight ahead sitting on the boat (facing the direction the boat is traveling in. When I stop paddling and look around left and right, my marker will briefly face north or south but never west. Once I leave boat, my marker displays the correct direction which I am facing. Back on the boat, I look at map and paddle in a circle, marker constantly faces East.