[Ruthless] Sulphite Intoxication does not grant movement speed

Both the Packed with Energy Atlas Passive and the Sulphite Intoxication buff tooltip state that Sulphite Intoxication grants +15% movement speed per stack. However, the buff does not actually grant any movement speed even though it should.

The 3rd and 4th screenshots show my character's identical movement speed (+67%) with and without 3 stacks of the buff.