If you are hitting the API successfully and it's not returning any data, then its due the API client not having enough permissions. in  Settings / Administration / API Clients select the Client Name from the list, and take a look at the roles assigned, if there is no roles or the client is given a role that does not have sufficient permissions, then the data will return empty.  I know this is from a year ago, but at least it's here in case someone else has a similar issue.  ... View more