Brush broken in certain worlds??

[CoolCuzzy]

Hey! So i made a brush (i did //brush sphere 5 block;purple_wool(sand)) to replace purple wool with sand. We did it in a certain world and when we do //undo the area around the sphere within a selection ina cubed space gets turned to air and everything just becomes broken! Here are images:

It works in out non build world and this issue has never happend previously but all of a sudden while attempting to replace using the brush it occurs. Is there a resolution for this?

Also IGNORE THE UI