Wow, a lot of people have had problems with this achievement. On my old profile, it unlocked on the bridge crossing on the way to the boss fight. This profile however is a different story. Gonna try the solutions in this thread later and see if I have any joy. Last one for the 1000g.
Back on Minecraft, and playing Creative. If you are a regular player, and can build half decent or better, get in touch. Want to get a group together to expand my world.