для правильного использования wp_editor используйте его так:
// add the admin settings and such
add_action('admin_init', 'wp_your_plugin_admin_init');
function wp_your_plugin_admin_init(){
register_setting( 'wp_your_plugin_settings', 'wp_your_plugin_settings', 'wp_your_plugin_settings_validate');
add_settings_field('wp_your_plugin_user_custom_text', __('Enter your message','wp_your_plugin'), 'wp_your_plugin_user_custom_text', 'wp_your_plugin', 'wp_your_plugin_main');
function wp_your_plugin_user_custom_text() {
$options = get_option('wp_your_plugin_settings');
$settings = array('media_buttons' => true,'textarea_rows' => 5,'textarea_name' => 'user_custom_text');
wp_editor( $options['user_custom_text'],'user_custom_text', $settings );}
// validate
function wp_your_plugin_settings_validate() {
$options = get_option('wp_your_plugin_settings');
if ( empty($_POST['user_custom_text']) ){
$options['user_custom_text'] = __('Enter your own content, it will be below the original message','wp_your_plugin');// as set when the plugin activated
}else{
$options['user_custom_text'] = wp_kses_post($_POST['user_custom_text']) ;}// u need to Sanitize to be able to get the media to work