so as the questions states, what im trying to accomplish is to fetch only the posts that do not have a featured image set. i tried looking through the docs and i noticed you can use the - symbol to exclude something from your argument, but that isn't working for me. Is there something else i can do in my query args to achieve this? thanks for your help!
$mediaargs = array( 'post_type' => 'media', 'posts_per_page' => 1, 'paged' => $paged, 'order' => 'DESC', 'orderby' => 'modified', 'meta_key' => '-_thumbnail_id', );