I have 3 pieces of a basic map markers each pointing into different cardinal direction.
Your circle has a big bounding box. The circle is not alone. But your major problem is the group. It's not a single shape. You subtract also the upper shapes of the group from the lowermost.
Have several copies of the circle at the same place. Ungroup. Subtract one circle from one item at a time. Alternatively unite the members of the group before the minus operation.
How to unite: Ungroup your shapes. Select the shapes. Then in the pathfinder panel click Unite. If the result has separate parts, they are now a group that can be ungrouped.
I see you have already chosen best answer, but there's another way to do this without copying lots of circles, and since I already worked on it I may as well post it here.
- Select all the parts that make up the blue marker shape.
Path Finder, and in the path finder, click the
- Place the black circle on top of the shape.
- Select both blue marker shape and the black circle, and in the path finder click the