Acuity mod of Ascendency skill (Sorcerer)

The Acuity mod of of the Sorcerer skill Ascendency is not working as described. The mod is supposed to set the mana cost of all spells cast while Ascendency is active to a cost of 5 mana. It is not doing that. The cost of my spells is the same whether I take that mod or not. The rest of the mod is working as described from what I can tell though.

As a correction I think it is actually the base skill Ascendency that is either not described correctly or not functioning as intended. When Active, spells are supposed to cost a flat 5 mana Plus the constant 25 mana per second drain. Acutity removes the drain. Either way, the cost of the spell is NOT being set to 5 mana.