Dragon Bugged

On my family Minecraft world, I fought the dragon but there was something odd. After eliminating it, it was transparent in the death scene. My brother fought it again later and the same problem occured. I fought it today and somehow it gave the egg and base xp as if it was the first fight. I was unable to capture an image of it occurring but I can show the egg and my levels with the multiple portals unlocked from previous battles.