When you upload a offline map to creative the chunks don't generate properly. They orientation of them aren't correct when transferred to online. I tested this by making a square that was in 4 different chuks and when i uploaded it to online private maps it was completely messed up.
Also on a side note, there is a current problem where one of my private maps was hacked/duplicated and published by someone else, it was a block for block copy. For a more detailed description check out my other bug report post. It would help if an admin or developer could look int this.
Weird. I never really play creative unless I'm trying out base designs and red stone tests but that's in single player creative
Hello, thanks for bug report. We will disable this functionality for some time to fix it. Have a nice day!