Outlook REST API returns events without start and end dates

When requesting GET https://outlook.office.com/api/v2.0/me/calendars/{calendar_id}/events the response (for some events) does not have a Start and End date.

The full structure for such events is as follows:

{
  'OriginalStartTimeZone': None,
  'End': {
    'TimeZone': 'tzone://Microsoft/Utc',
    'DateTime': '0001-01-01T00:00:00.0000000Z'
  },
  'HasAttachments': False,
  'ResponseRequested': True,
  'ShowAs': 'Free',
  'Recurrence': None,
  'Start': {
    'TimeZone': 'tzone://Microsoft/Utc',
    'DateTime': '0001-01-01T00:00:00.0000000Z'
  },
  'BodyPreview': '',
  'AllowNewTimeProposals': True,
  'Location': {...},
  'Attendees': [...],
  'TransactionId': None,
  'Type': 'SingleInstance',
  'ResponseStatus': {
    'Response': 'NotResponded',
    'Time': '0001-01-01T00:00:00Z'
  },
  'Body': {...},
  'OnlineMeeting': None,
  'IsRoomRequested': False,
  'OnlineMeetingProvider': 'Unknown',
  'IsCancelled': False,
  'IsAllDay': False,
  'ReminderMinutesBeforeStart': 0,
  'Subject': '...',
  'Categories': [],
  'LastModifiedDateTime': '2020-03-11T18:31:15.548Z',
  'AutoRoomBookingOptions': None,
  'OriginalEndTimeZone': None,
  'CreatedDateTime': '2020-03-11T18:34:34.259429Z',
  'IsOnlineMeeting': False,
  '@odata.id': '...',
  'IsDraft': False,
  'WebLink': '...',
  'ChangeKey': '...',
  'SeriesMasterId': None,
  'IsOrganizer': True,
  'iCalUId': None,
  'AutoRoomBookingStatus': 'None',
  'Locations': [],
  'Id': '...',
  'IsReminderOn': False,
  'Calendar@odata.associationLink': '...',
  'Calendar@odata.navigationLink': '...',
  'Importance': 'Normal',
  'Organizer': {...},
  '@odata.etag': '...',
  'Sensitivity': 'Normal',
  'OnlineMeetingUrl': None
}

Is this normal behavior? If so, how can this be displayed?

How can I create such an event to reproduce it?