It says "While in heavy stance....you do not lose control upon taking heavy hits and cannot be knocked back".

I do lose control and do get knocked back. 

Does the perk not work?  Does the sentence not mean what it says? 

I haven't taken those in favor of more damage perks but from the last time I used them you are only immune to stuns from blue attacks but still get knocked back from red attacks.

Every single one of those perks are a lie and every single one needs to be reworked. None of them are worth taking over the other options. "Perk rework" my ass.

So what are the phrases: 

"You do not lose control"

"Upon taking Heavy Hits"

"Cannot be knocked back"

Supposed to mean?  They're sprinkled all over various perks.  Do certain perks with this phrasing work?