Google Email RentalCarReservation Schema markup not showing up in Calendar - schema.org

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": "firstname#email.com"
},
"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": "[phone]"
},
"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": "[phone]"
},
"dropoffTime": "2022-03-11T10:00:00-01:00"
}
</script>