Because of the tool diameter, it won't get into the sharp corners of the star. There are 2 ways around this. First would be to use the fillet tool with the smallest diameter you can use to cut the thickness of the star, and fillet the corners of the star. The second way would be to flip the board over, and cut the star using a sharp v-cutter, then v-carve the star, so that it can be glued in from the back. There's a few inlay articles in the Vectric forum about this.