I can confirm this as well. First of all, in creative mode, I located the End and defeated the Ender Dragon to see what it was like before trying it in survival. I then recently defeated the Ender Dragon in survival and realized I did not get "The End?" achievement (and therefore I did not get "The End" achievement either). So I entered the portal many times and still nothing. So I was thinking maybe because I did it in creative mode, it will not unlock in survival mode either. I play on PC, non-pirated, and never used any mods. Totally vanilla.
Kasaioni
I can confirm this as well. First of all, in creative mode, I located the End and defeated the Ender Dragon to see what it was like before trying it in survival. I then recently defeated the Ender Dragon in survival and realized I did not get "The End?" achievement (and therefore I did not get "The End" achievement either). So I entered the portal many times and still nothing. So I was thinking maybe because I did it in creative mode, it will not unlock in survival mode either. I play on PC, non-pirated, and never used any mods. Totally vanilla.
http://i.imgur.com/Po8a0.jpg