Thief problems with stealth

During stealth I can understand a previous skill from the opponent hitting me however, I do not understand while in stealth how the opponent can still target me and hit me while im clearly not in the same spot. Iv seen the someone attack me. And then travel on lock and a ranger still snipe me while im in stealth. Thats a problem. A previous attack is ok. but an attack after that? And they can still launch at your exact direction is horrible.