Eloqua Application REST API Contact Update Call Failing

Hello,

Hello,

I'm looking for help with using the Eloqua REST API call for updating a Contact (https://docs.oracle.com/en/cloud/saas/marketing/eloqua-rest-api/op-api-rest-1.0-data-contact-id-put.html)

I'm making the following call to update an Eloqua contact with ID=59 but it always returns a 400 Validation Error.

URL: PUT {site URL}/api/REST/1.0/data/contact/59

Body:
{
"emailAddress": "jane.doe@gmail.com",
"firstName": "Jane",
"lastName": "Doe"
}

Response:
[
{
"type": "ProgramError",
"message": "endpoint identifier 59 != to object identifier 0"
}
]

I have tried this with a number of different contact IDs (both of existing contacts and non-existent IDs) and I always get an error of this form. I have also varied the fields included in the body of the request and no change.