I have the same problem with invisible polys on about 1/3 of the items I import into poser - especially the larger ones. Sometimes converting from OBJ to DXF or another format & back before importing seems to help. Sometimes flipping normals using the grouping tool inside poser helps. Sometimes nothing helps. I've even had the problem with some of the Poser-ready 3D Meshes I've purchased here & there. Just about all of them will render pretty decently, but I spend more time in texture shaded mode & I'd love to see things as WYSIWYG prior to rendering.