Just a wild thought but try decreasing your presser foot pressure, just a tiny bit. Poly batting sometimes has a tendency to slide, between the two layers of fabric. You might also try thread-basting a bit, to see if that holds better than pins.
Welcome to the Quilting Board!

Just a wild thought but try decreasing your presser foot pressure, just a tiny bit. Poly batting sometimes has a tendency to slide, between the two layers of fabric. You might also try thread-basting a bit, to see if that holds better than pins.
Neesie
By all means let's be open-minded, but not so open-minded that our brains drop out.
~Richard Dawkins
I think it might be the decorative stitch that is causing the problem.
i think polyester batting is fabulous for hand or free-motion quilting.
i gave up trying to use it for quilting with a walking foot.
I Quilt, I Nap, I Quilt Some More ... Aaaaah, The Good Life!
I also have an eddres you can use if you need to contact me with questions or suggestions that relate to our community: patricej@quiltingboard.com
this is what I do and it works well for me....after I have sandwiched all the layers and basically i only pin around the outside edge of the quilt all the way around....then I iron it...the back and the front....you will see how much more excess fabric you have then you thought.....then re-pin...I just use an open toe foot for the quilting...have better luck then using a walking foot....good luck..hope this helps...
Have you tried glueing the layers together or spray-basting them together to make sure they do not move on you>
I also think the decorative stitch may be an issue. Because decorative stitches go back & forth & side to side, your walking foot may not be able to keep up. Not all stitches are appropriate for quilting. The poly batting allows more shifting than cotton. You can also try to reduce your presser foot pressure.
"I do not understand how anyone can live without one small place of enchantment to turn to."
Marjorie Kinnan Rawlings
The stitch I am using is under the category of "Quilting Stitches". So silly me, just assumed that meant to use when quilting.
I have tried everything. Reduced the pressure, made it harder. Rethreaded, rewound, cleaned it. You name it. It is a Janome 12000 Memory Craft. So for what it's worth it should be a fabulous machine to use. Well, it isn't. Give me an old fashioned machine like my Featherweight any day for great stitch and tension. Unfortunately I've not been able to get it to quilt.
I like to use the so called quilting stitches instead of SITD because they allow room for error. Also, they add a little something on a kids quilt.
I've also noticed through all this that the stitch doesn't look so great on the back. Which indicates to me that the upper thread tension is off. Is that right?
Have you tried that stitch without the walking foot?
I was told no walking foot for decoratives also to stabilize the stitches.
(\ (\
(>':')
(,( )( )