The Sinch Contact Center Restful Contact Management Interface (CMI) API shows the operational interface for Contact Center provides data of contacts and their content.
It's a bit difficult to say what might be the reason for this. Could you please contact Customer Support at https://jira.digitalinterconnect.com/servicedesk/customer/portal/35 so we can have a look at the situation in your environment. In case you haven't registered for the portal, you can do so at https://jira.digitalinterconnect.com/servicedesk/customer/portal/3/user/signup. Thank you!