Couple of extra notes. First of all, I found that this effect happens sometimes when vertex does not seem to lie right on the traverse line, but very close to it as well. Secondly, now I recall that there were moments in various games when missiles shot into the room corner dissapeared; now I guess they just passed through wall then.

When using PathTraverse there's a chance that line get straight through the vertex or a number of vertices. It seems that in that case no line(s) are counted intercepted. This may lead to unexpected results especialy if these vertices were joints between solid lines. I believe this could be fixed somehow, for example checking all vertices in each passed sector to find these that lie on the traversing path... or maybe there are better ways.