End Crystal Spawning

When you fight the Ender Dragon i noticed that some of the end crystals did not spawn in, i noticed this mainly on the caged crystals as one did not have a crystal in it while the other did, i recorded this video and i got the glitch on the first try so it should be easy to reproduce

Youtube link:
https://www.youtube.com/watch?v=oFyfoSR7N9M

Also i fought the dragon afterwards, it never breathed any dragon breath, not to sure if intentional aswell.