Wrong result of BRepExtrema_DistShapeShape function

Hello Guys,
I have strange result for a couple of shapes. Both of them were translated on some vector before BRepExtrema_DistShapeShape.

Please look at screenshot. First solid is white, the second solid is front "wall". Yellow vertices are result of algorithm. There are 8 vertices. And looks like there is phantom of white solid, shifted on some vector.

What could be the reason of so strange behavour?

Thanks.
With respects, Eugene.