My creative world won't load

Loading or creating ANY world on Creative Mode yes kills achievements. Microsoft is super strict about having no ways to cheat with gamerscores. So yeah the game developers had to make it that way. Don't worry I have a main world and me and lots of my friends
have played on it and will make sure I never load that world on Creative Mode quite easy to get achievements on that world. I also have a new main world on creative mode which a bunch of friends have joined. And when a world has achievements disabled ITS PERMANENT
for that world.

even easier when loading the world put it on creative and give yourself a stack.

you could just load up random worlds in creative, and when you find one you like, copy the seed and use it to make a new survival world....that'd be the easiest way to go about it I think.....anyway, I don't actually know if just loading and not saving in
creative would kill achievements...I'd think it'd be only creating or saving in creative that would do it, but yeah, I just don't know 100% sorry

No. Once you have either enabled Host Privileges or loaded the world in Creative Mode, both achievements and leaderboard updates will be disabled.

Here's something for you - I loaded up the warning screen, declined and started another world in Creative mode. This seems to have had the same impact of disabling achievements in my other worlds. This or Microsoft bungled syncing my saves onto their cloud.
Royally annoyed.