The fonts installed on Apple devices are not freely available on all systems, (Mac OS has support/licensing for all the fonts, and that’s why this issue is not seen when viewing the PDFs on Mac OS). Because of this, the fonts can’t simply be embedded into the PDF. Instead, the PDF reader software must try to substitute a font with some other font that it knows about if it can’t locate the document’s original font(s). The Foxit PDF Reader seems to do a good job of locating substitute fonts.

We are investigating an alternative way to generate the PDF files for a future release. For the time being though, if you find another PDF reader that fixes the issue for you, or you find a substitute font that fixes your issue, please let us know about it at support@zymbiotic.com.