Why is a part of the icon filled in when importing an icon into a font?

Question

Icons

Hello. It was necessary to make an icon, but the experience in this is tiny, or rather, none. With the help of Google, it turned out to make an icon. Some I took ready-made, some my own. I collected everything in Figma, flattened it, I export it, the icon looks good in the browser, but when I upload it to the fontastic site to make an icon font, the icon is displayed with a fill in the end.
Tell me, what can it be?

Answer 1

Precisely all line elements are broken into layers? If the whole icon is one layer, then the font reaction is normal, because the checkmark inside the element has no connection with the general vector shape.