Mine wouldn't work that way. I had to use the dwg trueview converter for some wierd reason.Why don't you just do a save as 2010dwg in your normal autocad program?
There is an other issue with this file: format of 2018 year. We are planning to support new format versions of dxf/dwg in the future but not soon. You can save the file from AutoCAD as 2013 year format (for example) and it will be imported correctly to J-Filed.I am on the latest release version. Here is a link to a .dxf that wouldn't load in the LS.