[SOLVED] EventReservation won't reschedule/cancel

I can schedule events using gMail markup, but...

If I attempt to reschedule an event, it just makes a second copy at the new time, and leaves the original event intact.
If I attempt to cancel an event, nothing happens.

An example of what my confirmation looks like:

<div itemscope="" itemtype="http://schema.org/EventReservation">
  <meta itemprop="reservationId" content="Example967585">
  <link itemprop="reservationStatus" href="http://schema.org/ReservationConfirmed">
  <div itemprop="underName" itemscope="" itemtype="http://schema.org/Person">
    <meta itemprop="name" content="Sam Brown">
  </div>
  <div itemprop="reservationFor" itemscope="" itemtype="http://schema.org/Event">

    <meta itemprop="name" content="The Return of the Sam Exclusive Experience">
    <meta itemprop="eventStatus" content="http://schema.org/EventScheduled">
    <meta itemprop="startDate" content="2019-12-20T10:00:00-08:00">
    <meta itemprop="endDate" content="2019-12-20T11:00:00-08:00">
    <div itemprop="location" itemscope="" itemtype="http://schema.org/Place">
      <meta itemprop="name" content="851 81st Avenue">
      <div itemprop="address" itemscope="" itemtype="http://schema.org/PostalAddress">
        <meta itemprop="streetAddress" content="851 81st Avenue">
        <meta itemprop="addressLocality" content="San Francisco">
        <meta itemprop="addressRegion" content="CA">
        <meta itemprop="postalCode" content="94105">
        <meta itemprop="addressCountry" content="SE">
      </div>
    </div>
  </div>
</div>

Here's a sample reschedule markup:

<div itemscope="" itemtype="http://schema.org/EventReservation">
  <meta itemprop="reservationId" content="Example967585">
  <link itemprop="reservationStatus" href="http://schema.org/ReservationConfirmed">
  <div itemprop="underName" itemscope="" itemtype="http://schema.org/Person">
    <meta itemprop="name" content="Sam Brown">
  </div>
  <div itemprop="reservationFor" itemscope="" itemtype="http://schema.org/Event">

    <meta itemprop="name" content="The Return of the Sam Exclusive Experience">
    <meta itemprop="eventStatus" content="http://schema.org/EventRescheduled">
    <meta itemprop="startDate" content="2019-12-21T10:00:00-08:00">
    <meta itemprop="endDate" content="2019-12-21T11:00:00-08:00">
    <div itemprop="location" itemscope="" itemtype="http://schema.org/Place">
      <meta itemprop="name" content="851 81st Avenue">
      <div itemprop="address" itemscope="" itemtype="http://schema.org/PostalAddress">
        <meta itemprop="streetAddress" content="851 81st Avenue">
        <meta itemprop="addressLocality" content="San Francisco">
        <meta itemprop="addressRegion" content="CA">
        <meta itemprop="postalCode" content="94105">
        <meta itemprop="addressCountry" content="SE">
      </div>
    </div>
  </div>
  <meta itemprop="modifiedTime" content="2019-12-19T15:15:40-08:00">
</div>

Finally, a sample cancellation markup:

<div itemscope="" itemtype="http://schema.org/EventReservation">
  <meta itemprop="reservationId" content="Example967585">
  <link itemprop="reservationStatus" href="http://schema.org/ReservationCancelled">
  <div itemprop="underName" itemscope="" itemtype="http://schema.org/Person">
    <meta itemprop="name" content="Sam Brown">
  </div>
  <div itemprop="reservationFor" itemscope="" itemtype="http://schema.org/Event">

    <meta itemprop="name" content="The Return of the Sam Exclusive Experience">
    <meta itemprop="eventStatus" content="http://schema.org/EventCancelled">
    <meta itemprop="startDate" content="2019-12-21T10:00:00-08:00">
    <meta itemprop="endDate" content="2019-12-21T11:00:00-08:00">
    <div itemprop="location" itemscope="" itemtype="http://schema.org/Place">
      <meta itemprop="name" content="851 81st Avenue">
      <div itemprop="address" itemscope="" itemtype="http://schema.org/PostalAddress">
        <meta itemprop="streetAddress" content="851 81st Avenue">
        <meta itemprop="addressLocality" content="San Francisco">
        <meta itemprop="addressRegion" content="CA">
        <meta itemprop="postalCode" content="94105">
        <meta itemprop="addressCountry" content="SE">
      </div>
    </div>
  </div>
  <meta itemprop="modifiedTime" content="2019-12-19T15:26:23-08:00">
</div>

Other than being run through a translator to take them out of Quoted Printable format, those are live examples, cut&pasted directly from the eMails they were sent through.

All three markups pass the testing tool at: https://search.google.com/structured-data/testing-tool#

A subset of the things I've tried:

Using the sample code from the markup page.
Updating that code to the newest versions I can find at schema.org. ** e.g. Changing reservationNumber to reservationId. ** e.g. Changing the reservation status to match the ReservationStatus types shown on schema.org rather than the versions from the markup tutorial page.
Testing by eMailing the markup to myself, using the markup email testing script at https://developers.google.com/gmail/markup/apps-script-tutorial and the sample code from the markup eventReservation page.
Swapping from the microdata example to the json+ld example when using that self test script.

I'm stumped for more things to try.