WP 3.4 has missing photo data

Having figured out the issue, I’d like to update this question. The issue stems from previous versions of WP not including the _wp_attached_file meta key when uploading media, which 3.4 now seems to require.

Below is PHP code for looping through the database, verifying the presence of both the key and image file, then updating the database were possible.

// descend through the database
$updated = 0;
$skipped = 0;
$error = 0;
$upload_dir = wp_upload_dir();

$sql = sprintf("select * from %s where post_type="attachment"", $wpdb->posts);
$all_attachments = $wpdb->get_results($sql);

foreach ($all_attachments as $attachment) {
    // get the meta value
    $meta = get_post_meta($attachment->ID, "_wp_attachment_metadata", true);
    $file = $meta['file'];

    // verify that the file exists
    $file_path = $upload_dir['basedir'] . "https://wordpress.stackexchange.com/" . $file;
    if (!file_exists($file_path)) {
        $error++;
    }
    else {
        // add the meta value, which returns false if it already exists
        $adding_meta = add_post_meta($attachment->ID, '_wp_attached_file', $file, true);
        if ($adding_meta)
            $updated++;
        else
            $skipped++;
    }
}
echo '<div id="message" class="updated"><p>' . sprintf("%d attachments were updated, %d were skipped and %d had errors.", $updated, $skipped, $error) . '</p></div>';