the first time I encountered the glitch, the ender dragon would hit me above ground, and when I went to my under ground tunnel, it would hit me again and again. Then it eventually stopped moving, though it still flapped its wings. It soon disappeared and the exit portal appeared, but not the dragon egg, or the XP, or the end island portal. Because I needed to have the dragon egg, I made a new file. I eventually got to the dragon again, but it still hit me when I was underground. I got a recording that showed the ender dragon thanks to my armour keeping me alive.