After I finished with the Ender Dragon I attempted to summon him once more using the end crystals. However I didn't place them in the proper locations at the time and inadvertently discovered a new bug because of it.

Placing end crystals in their previous locations THEN attempting to place them in the proper areas by the exit portal will create a game breaking bug where it makes it impossible to call the dragon once more, thus blocking any possibility of fighting it or farming its resources.