to_obj() generates model with missing windows

[ghost]

When a surface has more than one subsurface in an .idf file, only the first subsurface appears in the converted .obj file.

The image below shows an example featuring a shoebox building with three windows on the South wall. On the left is the expected result, and on the right is the actual outcome.

Files to reproduce the example above: files.zip

From what I could gather, I am assuming the source of the issue is in the obj.build_surface_with_subsurface() function.
Any help would be much appreciated!