From his recent posts in the SCF Developers forum, he seems to be working a lot with dimension objects, and having issues getting a reference to what objects the dimensions are attached to. (Hence my snippet above starting from a dimension object.)
EDIT: Okay, he reposted his dimension query here, and you’ve seen it, and logged a API issue.
How can I tell to which instance a dimension is attached?
So I think this has resulted from his issues regarding that. He keeps using the term “not what he is expecting” with regard to the empty instance path array returned, so what I think is happening, is that InputPoint is returning the dimension object’s path which is empty because it is in the root model context. But he is “expecting” the method to return the instance path of the geometry object to which the vertex belongs.
Perhaps he should be using PickHelper instead and iterating the arrays of picks ?