TheNLS error is due to a different language being used in the drawing. for more on NLS and possible solution you can google it or look at threads similar to this. -us/windows/forum/all/nls-files-are-missing-or-corrupt/4d1a80ba-a282...
As far as Sketchup, that is a Teigha problem. Teigha sells its dwg interpreter to products like sketch up so they can get away with using dwg without licensing from autodesk. Its a non trusted dwg format and so its a use at your own risk situation.
When opening a new file (without any drawing )
its opening normally. When trying to use a saved Auto cad file ( drawn from
the same 2018 version. Auto cad a few hours back ) its prompting for
NLS...files.
The saved auto cad file shows its normal saving versions. But trying to
import such files to Google SketchUp is says the saved versions are not
.dwg / .dxf or write protected.
3a8082e126