Subtractive Box is invisible even though Additive is visible?

Hi there, When I use the Geometry Brush set to Box and Subtract, the box disappears.
It is visible when I select Additive.
I tried to set it at the beginning i.e. in the Geometry->Box and select Subtract in the bottom right hand corner of the window(instead of the drop down menu in Brush Settings) but it makes no difference.

Any ideas?

i was looking at this page here:

and apparently these “additive/subtractive” only works on other Brush Objects. So it might not work if your walls are not already brush objects

ALSO, something i noticed (and this is mentioned in that linked page) is that you need to create this from an EXISTING ATTITIVE SHAPE.

so when I just tried it out on my UE4 v4.19.2, for kicks i placed a subtractive box shape in the field, then an additive box shape, but this did not do anything

HOWEVER, if i DUPLICATED the element within the viewport, by clicking on the object and dragging on an arrow while holding down alt, then it actually did something to the additive box

this is just something i noticed, not sure if this will be helpful for you.

thanks a lot. Very helpful.

I thought that the tutor created the walls using normal cubes instead of a Geometry Box and then applied the Geometry Brush.

Thanks for your help and good to know for the future when I probably won’t be using Geometry Brush with created meshes.