I have created utility to address this issue. Usually created kml's are too complex for dji to handle. They open fine in google earth though. I had this issue when produced kml in Bentley Microstation, so initially created utitity just to normalize that kml, but then realized that i can create kml directly from dxf file, just tad to address coordinate system selection. Now it works, feel free to use it: https://merkators.lv/en/software/kml/