When I wanted to buy Mod Podge at the hardware store I was told they don't carry it
anymore as everybody just use Elmer's School Glue. So that's what I got.
I use a lot of Elmer's for basting my quilts and use the iron and no toxic fumes.
Maybe you could try that instead...dilute it with water if needed.
It could also be the fabric. They put all kinds of chemicals in them.
Might be a good idea to pre-wash your fabric.