Myanmar Font can't be embedded in PDF - only on Mac - licence free

I am preparing the lay out of a long Myanmar language document, but there is an issue with exporting to PDF which does not want to embed a font used.

In the screenshot below the problem is with WinInnwa but the same warning comes up with Art House fonts.

Zawgyi font is no problem but for titles and pull quotes I want to use a different font.

I use Innwa on a PC computer at another office, with PC this problem doesnt happen but it does on Mac.

The fonts are licence free, there is another issue but we can't find how to resolve it. Outlining all the titles won't be a productive option as that will hamper future edits and updates in the table of contents.