Try different needle types. I would normally use quilting needles for machine quilting, but try using a Microtex for machine quilting or a smaller 80 topstitch etc.
Also try a different needle size. Size up or down more than you might expect. The bigger the needle, the bigger the hole in the fabric....with the steam-a-seam layer, you might need to make adjustments.
When i try to machine quilt over items with steam a seam fusible I get skipped stitches. I've tried numerous needle and thread combinations. Does anyone have any suggestions?