Are all custom properties entered by API lists/array?

I’ve tried every one of those formats with no success.

Here is the current payload and what I get back.

{
  "data": {
    "type": "profile",
    "id": "XXXXXXXXX",
    "attributes": {
    },
    "properties": {
      "LapsedDate": "2024-10-04T00:00:00Z"
    },
    "meta": {
      "patch_properties": {
        "append": {
          "LapsedDate": "2024-10-04T00:00:00Z"
        }
      }
    }
  }
}

"properties": {
  "MailChimp Rating": 2,
  "LapsedDate": [
    "2024-10-04T00:00:00Z"
  ]
}

Another dumb question, have you verified in the profile page or segment builder that it’s *not* being treated as a date after sending it in via API?

Yes I have confirmed that. If I put the date in manually it segments correctly. If I put the date in via API it is treated as text for the segmenting. 

Manually it looks like 2024-10-04T00:00:00Z

API it looks like [“2024-10-04T00:00:00Z”]

If I take out the brackets and quotes manually from the api entered data it is treated like a date.

I’m getting the same problem with ANY custom properties I try to add via API - example:

https://developers.klaviyo.com/en/reference/create_or_update_profile

$payload = [
    'data' => [
        'type'       => 'profile',
        'attributes' => $attributes,
        'meta'       => [
            'patch_properties' => [
                'append' => [
                    'GN_custom' => 'value goes here',
                ],
            ],
        ],
    ],
];
$response = $this->client->Profiles->createOrUpdateProfile($payload);

I would expect my custom property `GN_custom` to have a value of "value goes here" but instead it is wrapped in an array like this ["value goes here"].

At first I thought it was a problem with their PHP SDK that we’re using, but after debugging that it appears to be just the way the API endpoint handles custom properties. It’s broken.