i'm very new to this but every SVG file I create, whether from Inkscape, Illustrator or MS whiteboard, the automated drawing first outlines the strokes then goes back and fills them.
Use the pencil or pen tool instead of the brush or calligraphy tool to draw your line art.
related threads: https://help.videoscribe.co/support/discussions/topics/1000070665
hope that helps,
-Mike (videoscribe user)