Can i have done something wrong? (Probably yes: you didn’t tell that your emf file was not produced on LibreOffice but on another source program. )
The downloaded emf file can be losslessly opened on LibreOffice 126.96.36.199. Export to wmf is well shown on Inkscape but not on LibreOffice itself.
Export to the wanted svg format is damaged (on LibreOffice and Inkscape as well).
Inkscape is not able to show the emf file losslessly. It is critically damaged.
The emf file can’t losslessly be converted or be broken on LibreOffice so my assumption is that you have imported the file from another source but not LibreOffice itself (did you mention that?).
There are lots of problems with svg and other formats on LibreOffice if imported from another source program(s). Think about the Wikipedia and its drawings in svg format. Regularly one is not able to edit them satisfyingly.
The only solution of proceeding may be to edit your emf file on its source program or to re-build it on LibreOffice and then to convert it to other file format(s).