field2
commented
4 years ago I believe these issues arise from the way svg's are saved in Illustrator. If I simple "Save As" and svg file, the build seems to work fine. If I Export for Screens, or Export Selected, and choose svg, the icons get corrupted like this. It definitely has to do with how the compound shape/path information is preserved, but I'm not sure what exactly causes this.
Props for spotting the issue, @chrisvanpatten.
The font builder apperas to be a little more picky than usual, so unless the SVG source files are very pure compound shapes, it will sometimes throw out some issues.
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