my end city portal totally disappeared, it is suppose to be at the top of the stairs in the picture and now it is gone.

I went onto the end island, i had to do a new entrance.  when i got to the top of the island, by end city portal was missing. the stairs i build to get to it was there, but nothing else.  i flew around the island, and there are no other portals at all to the end city. i hope you can see in the snip, it was difficult to get it in the picture.