In your Custom Post Type, do you setup_postdata( $post )
in your custom Loop? If not, has_post_thumbnail()
might not be defined/available?
EDIT:
Try adding:
setup_postdata( $post );
Right before:
$loop->the_post();
And then see if has_post_thumbnail()
returns true
?
Or, try passing the $post->ID
to your call to has_post_thumbnail()
?
has_post_thumbnail( $post->ID );