API does not always send fillGeometry (but sometimes does)

I have a VectorNode called “bird-torso.” When I select it, via a little test plugin that consoles outfigma.currentPage.selection[0];, I see that the node has vectorPaths and vectorNetwork data, just like it should.

When I look at the “bird-torso” node in the API response for the same document, it has no fillGeometry array is empty, no data. Looking through the whole response, there isn’t anything that describes the vector at all.

I have ?geometry=paths set on the API request, and fillGeometry is coming through fine for other vectors, just not “bird-torso”

The only real difference I can spot is that the “bird-torso” vector has this icon next to it:

A few questions:

1. Why do some vectors return fillGeometry and others don’t?
2. What does the “wiggly line” icon in the screenshot signify? Some “special” kind of vector? It seems to be a “generic” icon and doesn’t look anything like the actual vector.
3. Is there documentation somewhere that explains the relationship between vectorNetwork/Path and fillGeometry?