I’m not seeing stacks of frenzy applying to myself or to monsters, nor am I seeing an attack increase with every attack.
Is the skill even working now?
Working fine for me. It’s icon will appear in your buffs and will have a small number indicating the current stacks. The increase in attack is very small per hit making it less noticeable. You would only feel the increase if you take a look at your first hit and the hit after reaching 10 stacks.