When you do an array of cutting components you need to watch out for copying multiples to different faces.
A couple of instances of the same component tend not to cut when placed on different faces, whereas an array of one instance will pretty much cut anything it hits.
Here you see an array of 7 cuts even when it only hits the corner of the building, but array more than one to different faces and it fails to cut.
There is a specific rule about what works and what doesn't but I can't put my finger on it right now.
Cut Array.gif