Probably wrong thread to ask (though I'll admit it's lovely), but is anyone else having issues with Leg Sweep's stun not seeming to exist? Does anyone know what triggers it?

To be specific, at times when I perform Leg Sweep, I'll cause the damage and nothing else. I'm not getting any "Stun (Resisted!)" messages popping up. It just seems to act as if there actually isn't a stun component to the skill. It's quite rare that it happens. I usually try interrupting things such as 100-Tonze Swings if the tank is struggling to avoid them, and the stun of Leg Sweep not registering is... both painful and annoying. -_- Am I missing something here? Is there some separate accuracy check for the Stun? Or does it require you to hit from a particular angle, such as the Impulse Drive combo or Heavy Thrust?