Google Email RentalCarReservation Schema markup not showing up in Calendar

Question

I added a RentalCarReservation schema markup to my email, which has passed all the tests for whitelisting by Google, except that it does not create the calendar event automatically. I do see the event card above my email in Google and the action button is also working, but whatever I do, the event is not shown in the calendar (despite having 'Smart features' enabled in all Google apps).

https://www.google.com/webmasters/markup-tester/ lists no issues. I thought it might have something to do with the formatting of the datetime and switched this up a few times, but the card above the email shows the correct day and time.

What might I be doing wrong? Any help is appreciated!

<script type="application/ld+json">
{
  "@context": "http://schema.org",
  "@type": "RentalCarReservation",
  "reservationNumber": "11111",
  "reservationStatus": "http://schema.org/ReservationConfirmed",
  "url": "https://www.test.com/app/",
  "underName": {
    "@type": "Person",
    "name": "FirstName",
    "email": "[email protected]"
  },
  "programMembership": {
    "@type": "ProgramMembership",
    "memberNumber": "222222"
  },
  "bookingAgent": {
    "@type": "Organization",
    "name": "OrganizationName",
    "url": "https://www.test.com/"
  },
  "bookingTime": "2022-02-22T06:25:07-01:00",
  "modifyReservationUrl": "https://www.test.com/app/book?id=11111",
  "potentialAction": [
    {
      "@type": "CancelAction",
      "target": "https://www.test.com/app/edit?id=11111"
    }
  ],
  "reservationFor": {
    "@type": "RentalCar",
    "name": "Mini Cooper",
    "model": "Mini Cooper",
    "brand": {
      "@type": "Brand",
      "name": "Mini"
    },
    "description": "Ipsem Lorum.",
    "rentalCompany": {
      "@type": "Organization",
      "name": "OrganizationName"
    }
  },
  "pickupLocation": {
    "@type": "Place",
    "name": "Parkeerlocatie",
    "address": {
      "@type": "PostalAddress",
      "streetAddress": "Nijmegenweg 2",
      "addressLocality": "Almere",
      "addressRegion": "Flevoland",
      "postalCode": "1111AA",
      "addressCountry": {
      "@type": "Country",
      "name": "NL"
    }
    },
    "telephone": "+31000000000"
  },
  "pickupTime": "2022-03-11T07:00:00-01:00",
  "dropoffLocation": {
    "@type": "Place",
    "name": "Parkeerlocatie",
    "address": {
      "@type": "PostalAddress",
      "streetAddress": "Nijmegenweg 2",
      "addressLocality": "Almere",
      "addressRegion": "Flevoland",
      "postalCode": "1111AA",
      "addressCountry": {
      "@type": "Country",
      "name": "NL"
    }
    },
    "telephone": "+31000000000"
  },
  "dropoffTime": "2022-03-11T10:00:00-01:00"
}
</script>