Can't get OFFSET to work on complex 2D shape

See attached file. Right now a 2D shape, and I am trying to offset the edges. When I select an edge to offset, sometimes it offsets (just that one edge, not the whole shape) and sometimes it doesn’t (and there is a small circle with a line through it, indicating that it won’t apply the offset to the selected line).
What am I doing wrong? thanks –

DeWalt_Nose_Extension.skp (217.2 KB)

Which edges are you trying to offset? I see a stray edge that could be a problem up toward the right corner.

You would probably find it easier to do the offset if you fill in the faces first.

You can’t offset just one edge with the ‘Offset’ tool in SketchUp. You’ll need to select at least two connected (or more coplanar connected) edges. Or a single face. The edges are needed to define the plane in which the offset will be taking place.

Also the offset only offsets from the outer loop of a face. The holes (inner loops) won’t accept an offset unless you fill them in with a face and then offset to their exteriors.