The Nikosh font has the field "embeddable" set to "installable", but xdvipdfmx won't embed it into the PDF. Jonathan Kew suggests that this is because the "no subsetting" field is checked, which would explain why other fonts tagged as "installable" get embedded ok.
This problem is triggered when xe(la)tex has been run with the '-no-pdf' parameter set, and then xdvpdfmx is called on the command line (without the -E flag, of course). It also happens if you furnish an explicit xdvpdfmx command on the xetex command line, e.g. -output-driver "xdvipdfmx".
I attach a small xelatex file that demonstrates the problem.
Anonymous
Dvipdfmx always subset fonts to be embedded. If "no subsetting" is a requirement for embedding, then dvipdfmx can't embed the font.