I can verify that this is indeed a problem, I am trying to create a map and I am using the world seed Changaleon in the Old world style and I have trouble placing blocks in the corners ([-48, 100, 127], [-48, 100, -96], [127, 100, 127], and [127, 100, -96]) on Windows 10 Edition.
Same for me as well, happening on Windows 10 edition too.
Edit: Realm is back up and running
I can verify that this is indeed a problem, I am trying to create a map and I am using the world seed Changaleon in the Old world style and I have trouble placing blocks in the corners ([-48, 100, 127], [-48, 100, -96], [127, 100, 127], and [127, 100, -96]) on Windows 10 Edition.