I’ve been having this issue when exporting SVGs from Figma that use a stroke that has been outlined. A simple example of a 14x14 square with a 1px stroke:
<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
<path fill-rule="evenodd" clip-rule="evenodd" d="M14 2H2V14H14V2ZM1 1V15H15V1H1Z" fill="white"/>
</svg>
And when using that SVG in any icon font tool, the square ends up being filled.
I believe this is because of the fill-rule="evenodd"
. When I compare the SVG to how Illustrator exports it, it’s different:
<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
<path d="M14 2V14H2V2H14ZM15 1H1V15H15V1Z" fill="white"/>
</svg>
I know others have experienced this pain and have to jump to Illustrator to outline strokes, which is a shame https://github.com/tancredi/fantasticon/issues/135