All of the above but yes, I did have that problem recently and I believe it was due to the fabric content of the backing. Although it was 100% cotton, it was a cheaper fabric, I could tell by the feel, and it was stretchy and would develop bubbles no matter how much or where I secured the thing. I finally figured out that that was the problem and did a minimum of quilting on it and called it a day, it was a really weird fabric.