I initially started this in 18w43b, but it still persists in 18w43c, where when I go into the End Gateway, it just teleports me back to the initial End spawn platform, rather than further into the End. Also an added issue that fixed itself after a while, when I defeated the dragon in 18w43b, then left and went back to the End, the dragon respawned when I entered the End the second time, but every time after that this did not happen.