Upon defeating the Ender Dragon and going through the End Gateway to reach the End City, as the terrain generates for the first time around the Gateway on the other side my avatar drops from the gateway, taking a small amount of damage, and a building generates partly around the Gateway, replacing some of its bedrock blocks with End Stone Bricks, Pur Pur stairs, etc., rendering the gate broken and unusable. The only way out is to die in some way and respawn. Luckily I was able to stash my things in a chest taken from a treasure room, die, construct an ender chest in the Overworld and in the End City, move my stuff over, die again, and then reset the End and try again.
I tried repeating this process after resetting the End in my saved game and defeating the Ender Dragon again. I saved before entering the Gateway this time, so I could exit without saving and return to the point just before entering the portal again. The same result occurred. I exited without saving again, and repeated this once more. The same result occurred for a third time. Tried several more times. From what I have gathered, there is absolutely no way out of the End City island when this particular seed generates the End Gateway and then the terrain and structures for the End City Island.
I have little doubt that this problem will not be rectified without a patch of some kind, so I will be patient. I doubt my saved world will be particularly easy to play with in the End Island, but I can work around that now for as long as I wish to use this world.
Good luck and thanks for being attentive.