One of the first things that beginning Glowforge owners tend to get hung up on is thinking that if they want to cut something out, it has to be a shape with a stroke and if they want to engrave, it has to be filled.
This misconception comes from the way each type of image defaults in the Glowforge interface.
A stroke defaults to a cut and a fill defaults to an engrave - and that's great! If you want to work that way, it'll save you a couple of clicks.
However, if your image is a vector, you can choose cut, engrave, or score any time you wish. There's no need to go with the defaults or think that you can't change them.
So if it doesn't default to what you want, flex your clicking muscles and change it! :)