Akali's Twilight Shroud and Teleport

So I just finished a game as jg Hecarim (yes I know top is better, but its still fun to play jg as him) and the enemy top Akali did something interesting. I don't know if this is old news or not, but a felt this was at least worth noting. So when I on my way to help Rengar top, Akali was low on health and she used Twilight Shroud to cover herself and used teleport to get away. I figured the tele would show her but it didn't, instead she teleported away invisible so we couldn't kill her. Of course after that we used pink wards to stop that but that Akali wasn't stupid so it didn't go well for us. Any who I really don't know how I feel about the whole invisible teleport thing cause I thought riot made it so that no one could do that. I thought it was kinda clever not gonna lie, but I figured you guys should know that at least (unless they know already, idk). I don't know, do what you will with that I guess I wont be sore if they get rid of it or keep it either case. Just figured someone would want to know.