Hand Binding batik fabric
 

Glue that seam in place using Elmer's glue. Press it flat. Then SITD from the completed side. That will finish your binding nicely, and you can put away your hand sewing for this quilt. Use the correct color threads, and no one will ever notice.

Check the needle you are using. It needs to be a very sharp skinny needle to work well. Using beeswax on your thread can be helpful as well.
I have never tried using starch on batiks so that may be what is making it more difficult.

I needle turned batiks a long time ago and thought it worked great. Haven't had trouble with binding.
I agree with mom-6.......try a new needle or machine sew it, whatever works to get the job done.

It's been my experience starch or no starch ... its really tough to hand stitch a batik binding. I say go for the invisible thread ( probably smoke color would be best) and stitch in the ditch.

Have you tried roxanne needles. I use their applique needles and it glides right through my bindings, Im sure they have other types

Invisible thread is a nightmare when I try to use it to hand quilt. It is the needle as suggested above. Be sure to use a sharp and not between type.

I use a small thin sharp needle to bind batiks...or do any hand sewing with batiks. they are a tighter weave than we normally find with our quilting cottons. I do not generally starch my batiks, find no reason to they press so nicely with a little steam- but a good, new sharp fine needle should make a difference. personally I hate machine stitched bindings so I always hand stitch them unless the quilt is for a charity that requires a machine stitched one.

Keep testing needles till you find one that goes thru easily. I stitch only the back on my batik bindings by hand. The front is machine stitched. Plus, I just stitch the back fabric and the edge of the binding so, it isn't going thru the entire thickness.