Fixed: WordPress custom post type attachment not showing parent

Step-by-step fix: assign attachments to their custom post type parent

The most reliable way to fix this is to make sure attachments are programmatically assigned to their parent post during upload.

1. Make sure your CPT supports relevant features

When registering your custom post type in functions.php or a plugin, confirm it includes the right supports:

‘supports’ => array(‘title’, ‘editor’, ‘thumbnail’, ‘custom-fields’),

Without editor or thumbnail, the post edit screen may not behave like a standard post or page—and that can block the attachment-parent logic from triggering.

2. Automatically assign attachment parent on upload

Here’s how to hook into the upload process and assign the current post ID as the attachment’s parent.

add_action(‘add_attachment’, ‘assign_attachment_to_cpt_parent’);
function assign_attachment_to_cpt_parent($attachment_id) {
    if (!isset($_REQUEST[‘post_id’])) return;
    $parent_id = intval($_REQUEST[‘post_id’]);
    $parent_post = get_post($parent_id);
    // Only assign parent if it’s a specific custom post type
    if ($parent_post && $parent_post->post_type ===
‘your_custom_post_type’) {
        wp_update_post(array(
            ‘ID’ => $attachment_id,
            ‘post_parent’ => $parent_id
        ));
    }
}

This code runs when a file is uploaded and:

• Looks for post_id in the request (this is automatically passed by some uploaders like ACF).
• Validates that the parent post is of the correct type.
• Sets the attachment’s post_parent.

Replace ‘your_custom_post_type’ with your actual post type slug.

If you’re using a custom uploader that doesn’t pass post_id, you’ll need to add that logic manually or configure the uploader to include it.