I've created a custom category for items in the media libary. After I programmatically assign a category to an image ID, using wp_set_object_terms( $image_id, $cat_ids, 'my-custom_category', false ), when I check the custom category page. the categories that have assigned items show zero in the count column. Is there something else that has to be done when assigning a category so its category item count will display correctly?