Dialogflow ignores first message when replying with a card

Question

I am preparing a project in dialogflow and implementing everything on Facebook. It turns out that I want to send a previous message and then the card through fulfillment but for some reason it always sends only the card and ignores any message that I add to it either at the beginning or at the end, how can I fix it?

function ProbandoWebHook(agent) {
    const card = {
      attachment: {
        type: 'template',
        payload: {
          template_type: 'generic',
          elements: [
            {
              title: 'Título de la tarjeta',
              subtitle: 'Subtítulo de la tarjeta',
              image_url: 'https://acortar.link/GG8nfC',
              buttons: [
                {
                  type: 'postback',
                  title: 'Botón 1',
                  payload: 'Acción_1'
                },
                {
                  type: 'postback',
                  title: 'Botón 2',
                  payload: 'Acción_2'
                }
              ]
            }
          ]
        }
      }
    };

    agent.add("Hola");
    agent.add(new Payload(agent.FACEBOOK, card, { sendAsMessage: true }));
  }