Spell penetratrion in wotlk for shadow spells: does it work?

So looking through the bugtracker for the WotLK realms I see this:
- https://www.warmane.com/bugtracker/report/42951

So what are your experiences with shadow school spells being resisted (versus players) when you have adequate spell penetration so that they should never be resisted?
Is the bugtracker report linked above true?


And what about this: https://www.warmane.com/bugtracker/report/39685 ?
It isn't as serious as the previous one but is it still not fixed?