Have you tried loosening the top thread tension? My first machine was an ellageo, and I lowered it for every design. Also, are you pulling the material from the sides when you hoop? Shouldn't because it stretches out, then pulls back in when it's released from the hoop and that can cause puckering.

You could try using a sticky stabilizer. I use a wash-away sticky in the hoop (just that hooped so the sticky side also hooks on to the inner hoop). Then I use a "patch" of fusible interface (larger than the design but does not need to be the full size of the hoop) on the back of the garment. Then you stick the garment and patch to the sticky. To go even further I baste the garment/patch before I start stitching. I have not had many issues since I started doing it this way (except for poorly digitized designs - can't do anything for those). Sticky stabilizer is much stickier than a spray glue on another stabilizer. For the pre-made denium jacket - use a pair of old jeans, etc. for your test stitching. Good Luck.

The problem is the polyester in the fabric. A cotton/poly blend is not recommended for embroider (or at least quilting/embroidery). I don't remember where I read this quite recently, however the message was clear. Even with cotton or muslin, there is a chance for puckering. First of all because of fabric shrinkage. then thread shrinkage I use several types in one hooping. Sticky tear away and 2 layers of muslin/cotton is my favorite, of course with a healthy vilene (sulky) topping.
Also spray adheshive does not mix well with others. It must be exposed to air to dissipate. I do not think you will have any problem with the denim. Cotton Canvas, Duck and Denin all should do fine with a sticky bottom and vilene top (there is discussion that Peltex or cloud something for itchiness if next to the skin). If the problem exists it must be the machine tension. Always check your tension when changing thread types Good Luck!

Ladies have given me lots of fine advise, heading to the machine for some late sewing, Many thanks all!

follow this link to previous discussion regarding stabilizers.