"Sometimes after becoming a Made Man of the Salvatores, Boss Salvatore stops talking to me or reacting to anything unless I attack him or his people, then he will try to run away. Even if I steal his Oxygen Tank and/or plant the Poison Tank there is absolutely no reaction. The only notable thing he does is standing and waving his arms occasionally. When I get this bug Boss Mordino will claim Salvatore is still alive if I killed Salvatore in combat." The bug triggers if you click on Salvatore after becoming a Made Man; at that point his script freezes, failing to set the proper variable if he's killed and making an assassination impossible (you can test this by shooting him once and then checking your character sheet - if you're still a Made Man, the bug is active). If you save and load the game, though, he should be back to "normal" for as long as you don't click on him again, so all is not lost if you happen to set off the bug.