I am in the Town of Novac, Waited outside the ranch to find the killer of the cattle, that appears around midnight. I killed the Nightkin before he became visible, and picked up the "Screams of Brahmin". Talked to the Rancher, asked me if I found anything yet, only option available in the dialog is "not yet".

Are there more then one for this quest? Is this a bug? If it is a bug, is there anyway of repeating this quest? (Maybe a console cmd?) My last save is before entering the town, but sounds like its probably my only option.

Well, restarted further back. Now the NightKin just sits there. So I restarted the game, reloaded a previously saved game, and does the same thing. Just walks up to the cattle, and stands there. I can walk right up in front of him and he doesn't do anything. He comes out from behind a rock, doesn't go invisible this time. Just stands there, and right at 12:00AM, he looks around and then starts to walk towards the cattle and stands there, doesn't pull out his minigun or nothing. The beast is having some sorta absence seizure. lol.

Having the same problem on PS3. First time he just walked out without being stealthed at all but never did anything. Every other time he stays cloaked and just stands by the fence and does nothing.

I think I figured out how to trigger the Nightkin. Be sure to talk to Dusty and Alice until Dusty asks if you found anything yet and ask Alice what she knows about the mutilations. Be sure all of the text options you have with them concerning the issue are grayed out. I couldn't get this quest to complete until I did this, but it did work. I tried it 3 times to verify that it works.