听起来你在尝试获取一篇文章的分类术语。类别术语不存储在post meta中。

你可以使用get_the_terms(). 在本例中，$terms 将为category 与当前帖子关联的分类。您可以替换category 使用自定义分类名称。

$terms = get_the_terms( get_the_ID(), \'category\' );
if ( ! empty( $terms ) && ! is_wp_error( $terms ) ){
    echo \'<ul>\';
    foreach ( $terms as $term ) {
        echo \'<li>\' . $term->name . \'</li>\';
    }
    echo \'</ul>\';
}

WP_Term Object
(
    [term_id] => 2
    [name] => Alignment
    [slug] => alignment
    [term_group] => 0
    [term_taxonomy_id] => 2
    [taxonomy] => category
    [description] => Posts in this category test image and text alignment.
    [parent] => 0
    [count] => 4
    [filter] => raw
)