Sudden Infuriation perk probably doesn't work (Edit: Ok it works as intended)

For test I put rage on hit generation on my whirling assault, I ran at mosters for few minutes and just could not see my max rage changing. I checked if my dps is changing in any way, also nothing.
I tried put on gain rage when hit, stood for a minute in low level are taking a pouding, also didn't see it change.
Perhaps I missunderstand what this means?
My undertanding is that there is 4% chance to increase your maximum rage. Doesn't say for how long or for how much, but I assume it depends of how much you generated with that hit.
I also tried if it means I need pool avaiable so I actually literally gain it. But even with putting in support gem that drains my rage when using it whirling assault, I didn't see change to my max rage

if you gain any rage on hit there's a 4% chance you get max rage. If you at max already then nothing changes. this does not make your max rage higher mate

Yep... With generating 2 rage per hit, which was the least I could do. I would occasionally get full rage. I see. :)

No bug here i guess. Maybe feedback that some people might missundertand this description.