Return of Reckoning

Hello!
Holding grudges tactic looks bugged.
Tooltip says: every 4 seconds you gain a stack (max 3), each stack reduce exhaustive blows rage cost by 25%. Exhaustive blow spend 1 stack.

Bugs noticed:
1) I watch the rage bar (and amound of rage x/100 on tooltip). If you get 100 rage and 3 stacks, use ...