[SOLVED] Mailjet e-mail is empty when attaching a file to it

I have this bit of code that creates a calendar for a specific delivery, and then attaches it to an e-mail to be send. The problem is, when I attach the .ics file, the template breaks (no text, no pictures... nothing). Only the calendar file gets send (even though it does get send to the right e-mail).

  const event = await this.calendarService.getEventForDelivery(deliveryId);

  await this.sendMailjetTemplate('4069368', d.email, [{contentType: 'text/calendar', content: event}], {
    ASN: d.identifier,
  });