This is more about "fixing" something really annoying. When I went to the end for my first time to fight the dragon, I shot many times at many end crystals with my bow, but no matter how I aimed, the arrows just got stuck in the air near some of the crystals, it really frustrated me why some towers could be deactivated, so I pillared up to see if I could at least punch it, and then, suddenly, because I came closer, the cage loaded in. It seems like maybe the way the game works, is that the chunk hasn't been told to reload (the VBO or whatever), even though it has since been altered; has since spawned a cage around the crystal.

On a perhaps related note, an end gateway portal and exit portal had already spawned, but the dragon was still alive. I had never been to the end in this world before.