Admiral Valerius custom boss ailment threshold not functioning

I'm using a surfcaster with a hard hitting spell, Penance Brand of Dissipation

I can apply a 45% shock to Pinnacle bosses
But when fightning the Admiral, my shocks only go up to like 8%. that alone isn't enough for me to suspect a bug, but when the admiral is transitioning into his waves phase, for a brief moment before he is invulnerable i start to hit my high 30-40% shocks. I have a very high shock chance so, and my damage is lightning to cold, using a phys spell, so it's not a case of lightning damage's inherent wild ranges. I don't think it's a case of the energy of pbrand ramping, the energy doesn't seem to make any difference. Even when he is sub 10% health, my shocks still only apply 6-10% shocks. I have reason to believe the custom ailment threshold that is set so people can apply ailments to bosses is not functioning on Admiral Valerius.