BUG - Assassin skill points not affecting skills

[Onehander]

Sometimes skills act as if they had no skill points put into them, known ones:

Heart Stab (4 points) - sometimes takes you out of stealth as if it had no points in it. 
Shadow drain (2points) - sometimes knocks down as if it still were cyclone sweep.
Shadow dash (3 points)  - sometimes doesnt allow usage as if it had no skill points and hence on a longer cooldown
Lotus fury (1 point) - Should resist damage and status effects sometimes it does not
Backstep ( Double S) - Sometimes instead of pressing SS to activate it you actually need to click 4-5 times 

[Ratix]

Haven't experienced those personally but Sneak Attack seems to take you out of stealth regardless of how you assign your points.