Hi Finn,
DWG and DXF files not being supported by WAsP any longer. They are still supported if you only use one layer of contour lines, but anything beyond that will cause errors. Could you get the files in any other format than DXF? Perhaps ERSI shape files (*.shp), as they can be directly imported into WAsP Map Editor through 'Import' -> 'ESRI Shapefile maps'.
If not, there are online DXF to SHP converters that you could use as a quick fix right now.
It won't transfer the roughnesses however, meaning you will only get the lines in Map Editor, but you can simply choose each line and input the roughness you want.
I would also recommend you to use the previous version of Map Editor, which you will find as a stand-alone version here: https://we.tl/t-XbL5tEj5Nw
It is a temporary solution until we fix some stability issues in the last version.
I hope that works.
Best regards,
Katerina