Sometimes our machines want to "eat" the corners where we start the stitching, as in where you begin your X. Try holding on to your threads behind the foot, maybe pull a little, as you start to stitch until it gets going. Or try using a starter piece of fabric just in front of your block. Then you can start in the middle of the starter piece instead of a corner and just keep sewing right on to your block. I like pulling on the threads the best. Good luck!