Attached WMF file contains four LineTo records (with preceding MoveTo's), but programs that can read/show WMF files (I tried Paint, AutoCAD, Metafile Explorer) don't draw them. Three records use NULL pen, ok. But the 4th one uses a non-NUll pen, so at least it should be drawn.
The problem is that I try to parse the file myself for converting to another format and don't see a reason why the line should not be drawn. More details: coordinates are within header's bounds rectangle, no clipping is used.
The file: https://drive.google.com/file/d/1UIjslJK_6BGlrZ1tv6tBa5i9qvhuFSCc/view?usp=sharing