Running sketchup 2016 and can use substract on solids normally when the base shape was initiated with a rectangle or polygon, yet when I start with a cirlcle the subtract step appears to add the solids instead. I’m using the same technique.
Thanks DaveR, I don’t know how to create a file that shows animation such as yours. Here’s a screen shot illustrating my problem. I now know its not just about circles, as I can make a subtraction with a cylinder as seen in side wall of my outlet. But when I try the same procedure on the front wall I get what the appears to be the addition of my cylinder and wall.
cheers-