When doing a fill, often times you will want to position your Exit bead somewhere in the ‘middle’ of the shape. This means that the pattern will sew one part of the design, then go away and work its way back. If your fabric is being flattened by the thread, and you do not have undersewing for better coverage, this can leave what appears to be an ‘unstitched’ line across your fill. There are solutions for this – use more in the way of underlay, and/or move the exit bead to the opposite ‘end’ of the pattern. It is often better to ‘run’ to the next object after your fill than to have the fill exit in the middle.
Left: A fill with the Exit bead midway in the fill. This causes the stitching to go from one side, then the other as shown in the center image, which is shown using the sewing simulator (in this image it has sewn below, and is now working its way down from the top).
Right: Entry and Exit Beads are at opposite ends, which can help the fill provide a smoother coverage.