AppGyver Composer Backend Resources Fetching Columns failing

My Nodejs / Sails / MongoDB backend returns an array of json data but Composer Backend Resources Fetching Columns gives: Response code: 500.

Postman returns [

{
    "name": "Book2",
    "createdAt": "2014-09-05T00:31:57.016Z",
    "updatedAt": "2014-09-05T00:31:57.016Z",
    "id": "5409047da0ec9800002ffcdf"
}

]