I was trying the Ur Dragon for the 1st time in offline mode and was taking him down fairly easily, but when I got him down to the last health bar he flew off. I exited the area an re-entered and he appeared with low health, but no matter how many times I hit him he takes no damage (yes, I am hitting a giant glowing weak spot and there is blood coming out). I've tried exiting the game and reloading as well as turning my PS3 on and off but nothing works. It's getting very frustrating, is there any way to fix it?
I guess I'm not the only person with this problem. It never took any damage and I wailed on purple spot with blood coming out for 20 minutes. I went back one time and no difference. I was using a a red dragon forged dagger you get from defeating the dragon Grigori.