edit: reported to bug tracker: https://www.freecadweb.org/tracker/view.php?id=3962
I imported a mesh from mesh design workbench, rotated it around z by 180 degrees (menu: edit, placement, typed in 180)
then went to part workbench, created a plane.
switched back to mesh workbench. used from the menu: meshes, cutting, create section from mesh and plane.
expected result: section lies on the plane and goes through the mesh.
actual result: section lies outside the mesh (rotated around z). it seems to me it uses the original position of the mesh instead of the rotated mesh (tried it with different rotation angles to verify that)
OS: Ubuntu 16.04.5 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16093 (Git)
Build type: Release
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)