Sometimes polyhedra may appear uncomplete in the VRML output, when the range selected by the XYZR option is too small. Enlarging the box size should overcome the problem. However, sometimes you really want a small part of the structure. So that you have just to delete the undesired polyhedron. Many people have contributed to improvements.
Sources are still available for free.
So why not to improve the program by yourself. Bugs Possibly there could be different kinds of problems. This is unsufficient for claiming bug absence. Only those viewers enabling two-sided face lighting in VRML 1 should be used. Nothing such happened under Windows 3.11.