The Construction Assassination bug

[ELED3L]

First i reached the top of the building and killed the target, and its over, i can do what i want but the mission dont end.
So i restarted it, same happened, so i quited the mission, started it over from the beginning and its says i failed the mission because the target escaped when he goes up with the elevator.
WHAT THE F*CK, most bugged mission in this game.

+ i read on forums that some guy lost all his money because they put it on the stock market. I am happy the game restarting fixed the bugs.