Unfortunately, there is a known issue with how the GF interprets CorelDraw created SVG files that deals with the winding rules…the current work around is to either save the file as a PDF or rasterize the results of your vector drawing before saving the SVG file.
Another thing to take into account is that the white filled area in the center has to be subtracted from the blue filled area…the GFUI treats any vector fill color, even white fill, as something to be engraved.
There’s another mini-tutorial for dealing with vectors that explains it here:
Actually, at 600 ppi, the Glowforge handles raster engraves just as well as vector engraves, and you get more options for it…I tend to just recommend rasterizing the engrave portion of the design these days…it tends to be quicker.