Can not gain Power Charge in boss area using converted mod by "Way of the Stonefist"

I obtained the "Way of the Stonefist" node, and the mod "#% chance to Gain Arcane Surge when you deal a Critical Hit" was converted to "#% chance to Gain a Power Charge on Critical Hit". However, in boss areas, power charges are not generated even when critical hits occur.
They are generated without any problems outside of boss areas.
Am I the only one experiencing this problem?