The problem you've described sounds like a temporary issue and should have been resolved now. Please try again and let us know if the issue persists. help.minecraft.net/hc/en-us/… ^TM
I can definitely understand that, as we don't want you to lost your world either. Unfortunately, you'll have to keep an eye out on that page for any further updates and if they'll be new achievements with it. Thanks again. ^AS
I'm sorry if there are any delays on getting a response! We're working to respond to your ticket as soon as we can. Thanks for being incredibly patient! ^AS