I may have discovered an other one here.
Sometimes thin walls are not filled as expected by single extrusion.
No matter how high I set the infill there is just nothing in between inner and outer perimeter.
Playing with nozzle sizes (which I do not want) eventually I will at least get a solid infill at the top.
Only if setting 3 perimeters I will get a single extrusion infill.
Same goes for the cargo hold at the benchy where the gap is clearly visible in both the preview and the printed model.
Only with 3 perimeters it will get closed by single extrusion, but then I will have a benchy/object with 3 shells everywhere,
at least if not splitted in different processes.
I happily would provide a factoryfile which is already on my desktop.
But still I can not attach a 6mb file but getting an error for file being to big.