Snow Beast Glitch

I am trying to fight the Snow Beast once Issac finds where Ellie and the rest of the survivors are staying. I have read/seen how it is meant to be attacked. You must first shoot off the 3 tentacles in its back while avoiding being rammed, then shoot the 3 growths from its mouth. I have been told you must do this twice before it runs off, but I keep doing this same technique over and over to no avail. Am I doing something wrong? Or is it a glitch? I also experienced a glitch earlier in the game when Issac had to climb through the snow vehicle in order to avoid falling to his death, the "E" symbol did not appear until I read that in order to move past that scene I had to reset the settings for the game. I don't know if that makes any difference in this case. Help would be much appreciated. Thank you.