Can't Use 'Cast on Shock' Persistent Buff

Characer:Djpopple
Class: Invoker Monk
Server: Australia
Bug: Unable to utilise 'Cast On Shock' persistent buff. Despite having 98 spirit, it continues to say "Not enough spirit".
Have tried:
-Relaunching Game
-Relaunching Game with gems removed
-Removed gems
-Ensured I don't have any support gems equipped

-Can activate two other persistant buffs (Herald of Thunder, and Ghost Dance)
-Currently have +38 Spirit on Amulet