I have had some strange things happen like that. I was on Padres and was going to go to the back beach. There was a Navy dude standing right in front of the tunnel so I ran over and whacked him a couple times with my sword. He took damage and swung at me. Then all of a sudden he stopped swinging and stood there and said something about that pirate coward ran away. I tried to damage him again to no avail. He was invincible at that point. I was ticked. I am no coward!! And I'm standing right in front of you, you idiot!! Argh