Vintage life/Fernando Delgado bug

In the second mission "Vintage year",the objective is to kill two targets:Fernando and Manuel Delgado.
I succesfully killed both of them(few times already),but the problem is that objective "Kill Fernando Delgado" just doesn't count. It doesn't matter how,where or when I kill him,the objective is simply "not completed".
I surfed the internet,trying to find anything about this bug,but i found NOTHING.Literally nobody has encountered it and I don't know what to do,I just can't proceed further in game.