The entire hierarchy is added only when the 4th level is dragged to the filter area and not when higher level hierarchies are dragged. Why?
This is appropriate as per the functionality of ARC. When the lowest level hierarchy is dragged, then entire hierarchy is added because all the higher level hierarchies are also added. For example, when we drag the dimension at level two, both level2 and level1 dimensions are added. When we drag the dimension at level4, all dimensions above this level i.e. level3, level2 and level1 dimensions are added.