POST /api/v2/outbound/contactlists returns 422 INVALID_VALUE on valid JSON

NICE CXone API & Integrations
1

Why does the outbound contact list endpoint keep rejecting this payload with a 422 INVALID_VALUE error? I’ve stripped it down to the bare minimum required fields but it still fails.

POST /api/v2/outbound/contactlists
Content-Type: application/json

{
 "name": "test_list_berlin",
 "type": "CSV",
 "contactListItems": []
}

The docs don’t list any other required properties.