1.8/vanilla, java 1.7.0-67 64bit, single player
created world that I've been creating in for a few weeks on an imported small flat map. Tried cloning something 290 blocks away:
"/clone ~-291 ~ ~1 ~-291 ~ ~11 ~ ~ ~1"
It gives back:
Cannot access blocks outside of world
If I adjust that to -251, it works.
I thought I was hitting a worldborder, but I don't think that is true.
Not sure what else I can do to help troubleshoot this. Let me know.