Yes I agree there is something wrong with Stealth, I was complaining quite a lot from level 1-20 because it seemed like mobs were seeing me in stealth from a mile away... it wasn't that bad on Kronos which I was just leveling on previously.
Either it's broken on Nost, or Kronos is too good, I just leveled on there weeks before Nost re-released and can confirm I noticed the difference at low level too.