I narrowed it down now. One problem is that calling RN_DATA::Update() on an unfilled zone will successfully remove the zone, but then don't add it again, because there are no polygons in it.
The fix is to add an empty ZONE_DATA object in this case.
The other problem is that Fill_Zone is called in tools/point_editor.cpp without calling RN_DATA::Recalculate().
I narrowed it down now. One problem is that calling RN_DATA::Update() on an unfilled zone will successfully remove the zone, but then don't add it again, because there are no polygons in it. editor. cpp without calling RN_DATA: :Recalculate( ).
The fix is to add an empty ZONE_DATA object in this case.
The other problem is that Fill_Zone is called in tools/point_