Intersection Shape - Plane via BRepAlgoAPI_Section: Missing Edge

Hi, I want to calculate intersections between a shape and parallel planes using BRepAlgoAPI_Section.
As a result I want to get all intersection edges. This works correctly in most cases.
Just in one case one edge is missing.
The shape is not a solid, it consists of several (trimmed) faces, imported via IGES.
The location, where it happens, seems to be very similar to the successful areas, exactly the same faces are involved.
Please refer to screenshots attached.

I am using OCCT 8.0.0.

Any ideas on that issue?