See this:
https://forum.kicad.info/t/kicad-pos-file-ambiguity-for-symmetric-polarized-parts/5269/6?u=1.21gigawatts
and this from the same topic:
https://forum.kicad.info/t/kicad-pos-file-ambiguity-for-symmetric-polarized-parts/5269/12?u=1.21gigawatts