Error 403 (forbidden) when using get ticket API on a ticket in a new department

We use get ticket API and it works well.

We created a new department and when we try to use the same API on the tickets from this department, it fails with the error:
b'{"errorCode":"FORBIDDEN","message":"You are not authorized to access this resource."}'

When moving the same ticket to another department, the API works OK.

I tried to define the new department like the old one.

Is there a special way to define department so the get-ticket API will work?

P.S. The new department is not Private (shown in the Help Portale) – I am not sure it’s connected.