Are subdivision surfaces broken in SceneKit?

In Xcode, create open a new Scene graph and open it in the SceneKit editor.

Go to Editor > Create > Geometry > Box.

Open the Attributes Inspector and set the Subdivision level to 1, and enable Tessellation (optional).

I'd expect to see a chamfered cube, but instead there are gaps in the corners.

Is there a way to fix this?

Found something interesting.

If you create a cube in Blender, and export it as USDC, then subdivision works as expected.

Unfortunately, this does not work with Collada (.dae) or Wavefront (.obj). So, it must be that the USDC export in Blender produces geometry in a format that is compatible with the subdivision surface renderer in SceneKit (as does the SceneKit editor). I'm guessing this has something to do with indexed vertices.

Are subdivision surfaces broken in SceneKit?
 
 
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