I have a similar issue here;
Solidworks 2018 SP 2.0
-Try to export DXF/DGW from model, and have Custom Map Solidworks to DXF/DWG enabled in save options.
- Mapping dialogue appears - and I am able to set up layers and entities to map - and I am able to save a Map file (which has no file extension?)
- DXF exports correctly as defined in mapping file.
-I go to repeat process again, (same part, different part, doesnt matter) this time with map file location filled out in DXF save options
-DXF does NOT export as per the mapping file.
What gives?? Solidworks, why so glitchy plz fix