I'm having difficulty importing sets of books I created in Blender. In Blender, they look fine



but when I try to import them to Sweet Home 3D they look like this:



It seems like there's something weird going on with the normals, but they render correctly in every other program and as far as I can tell they're correct in Blender. When I turn on backface culling in Blender every face still renders correctly.

I uploaded the .obj file here if anyone would like to take a look and see what I'm doing wrong.