The description of the function FcFileScan states: "Scans a single file and adds all fonts found to set". But it doesn't add a font from the given font file.
The detailed bug description with the font file to download can be found at:
Created attachment 12222 [details]
The font file
Fontconfig may be configured to skip fonts for any reason; such fonts are never "found" by the scanning process. I've updated the documentation for this and the FcDirScan function to reflect this:
Whether fonts are found depends on fontconfig
poliy as well as the current configuration.
*** Bug 12950 has been marked as a duplicate of this bug. ***
*** Bug 12993 has been marked as a duplicate of this bug. ***