Did you try saving the as older format version of AutoCAD?
I use carlson survey 2015 with embeded 2013 auto cad.
Carlson's embedded CAD program is IntelliCAD, not AutoCAD. I suspect the problem is some type of compatibility issue from IntelliCAD. If you use some AutoCAD product like Autodesk DWG Trueview you should be able to convert the file and import it.
That is all inaccurate. Carlson makes an AutoCAD OEM version. Also I use intellicad routinely and have never experienced a compatibility issue with J-Field.
I personally called Carlson and they told me it was embeded auto cad not intellicad.
So just to beat the dead horse. I don't understand why I can't import a dwg anymore and the only thing I changed was I updated the LS.