Any particular reason Mac OS High Sierra won’t embed Zilla Slab font? I just tried to generate a PDF using the save to PDF option in the print dialog box but for some reason or another, the font won’t embed.

The font in question is Zilla Slab and so far, this issue doesn’t seem to impact other fonts on my system.
You have to install it on your Mac first.

brew tap bramstein/webfonttools
brew update
brew install ttfautohint
brew install bramstein/webfonttools/sfnt2woff
brew install bramstein/webfonttools/woff2