@EVAL не работает в поле "Значение по умолчанию" у ТВ

$v = $tv->get('default_text');

$v = $default;

<?php
switch ($modx->event->name) {
    case 'OnResourceTVFormRender':
        if ($resource !== 0) {return;}

        foreach ($categories as & $category) {
            foreach ($category['tvs'] as & $tv) {
                if ($tv->id != 2) {continue;}

                $formElement = $tv->get('formElement');
                $default = $modx->runSnippet('MySnippet');
                $formElement = preg_replace('/value="(.*?)"/', 'value="'.$default.'"', $formElement);
                $tv->set('formElement', $formElement);
            }
        }
    break;
}