Builders or anyone that might know what has caused this?

It is an easy fix, just recolor the columns. You don't have to change the colors, just click the column with color changer thing, I forget what it is called. I believe you have to also choose the color when the little box of color choices appear. Once you do that the column with automatically revert to the correct size. But yes it is a bug, and they said they are working on it.