Thanks for all the help. I have made a test sandwich with same batting and 505 as the real quilt. I lengthened the stitch, no IDT, and they are good now. But let me tell you, those bad ones in the real quilt were a nightmare to rip out.

I agree with these suggestions. I release the IDT when I quilt.

Are you using the Integrated walking foot?

Glad you asked. We were discussing this same problem at quilt meeting the other day and no one had an answer. I will share about the stitch length.

The total of fabrics together is too thick for the machine to feed properly.

Just wondering. Would decreasing the pressure on the quilt sandwich help? If the fabric appears to be pushing on the top, it could be pressure.

I have the same machine and had the same problem. Yes, try all of these suggestions first, and if that does't work, I had to take mine to the dealer for servicing and after that it worked. I almost always lengthen my decorative stitches though, as they are very dense for quilting. You don't need that many stitches to hold your quilt all together.

What does IDT stand for?

It's diff the presser foot you must lighten it up as much as possible...I've had the same issues and when I do that...all is well

I would say to make the presser foot tension tighter. Adjusting the stitch balance might help. And try using a presser foot that's flat on the bottom (your standard foot), then try a foot with the bottom cut out (embroidery or open toe foot). Sometimes one foot will work better than the other.