Single Post Breadcrumb not linking back to Custom Post Type Index?

If you read the codex you will see that is_single accepts post id’s / titles / slugs and

EDIT
If you are using two custom post types then WP will select the right single-POSTNAME.php And in your check you best check the posttype like:

if ( get_post_type() == 'postfolio' ) { /*do stuff*/ }