eNewsletter Builder Live Preview Blank over SSL

Single site Wordpress 3.6.
Wordpress SSL plugin set to force admin area to https.

Everything works (so far) except eNewsletter's Live Preview.

Turn SSL off, Live Preview appears.

Turn SSL on, No Live Preview

I want SSL in the Admin AND I want Live Preview, but eNewsletter doesn't agree.

It seriously only works in an unsecured backend? I've got to be missing something.