I get the same results. In LibreCAD it looks as a closed outline, but in KiCad there are two arcs on the bottom. I also imported it in FreeCAD (looks OK) , then exported it again to another .dxf file and opened that one in KiCad, with also the same faulty result.
After that I exported it as an .SVG from FreeCAD and imported that to, again with faulty result, but a bit different this time. In the screenshot below, the topmost shape is the DXF import, and the bottom shape is the SVG import.
What sort of entities are these supposed to be? If I draw “normal” lines or circles in LibreCAD, they don’t have any width. My LibreCAD knowledge is very limited, and I can’t even figure out how to make it show me what sort of entity an object is. In FreeCAD they are all “shapes”.
This may be worth a bug report, but it would be nice to know more about the original drawing first.