My friend did some beautiful blocks using batiks for the fused machine applique. Some of the fabrics just wouldn't do the blanket stitch properly...kept missing stitches.
The solution was to use a very small sharp needle, size 60 and an 80 weight thread in both bottom & top. This corrected the stitching problem.
She had already tried all the other ideas suggested here and more. The quilting shop where she bought the fabrics solved the problem. Seems everyone was having the same problem with skipped stitches on a few of the fabrics.