Some threads just do not play nicely! I hate when that happens and it is either take out all the quilting you have already done and changing to a different thread or soldiering on. I had one variegated quilting thread that gave me fits. Very linty and made a little ball behind the needle hole. I tried everything I could think of and finally just kept an eye on the needle and when I saw the ball/knot developing, stopped and re-threaded. I have never bought another spool of that brand for this reason.