I had the same issue. Of some reason the “data” is coming empty.
console.log(data); would not work
Instead of using the "data parameter" the json data can be retrieved through the oModel after attachRequestCompleted has been called or by using this.
Example json fetched from the back-end
[{"id":1,"address":"My address1"},{"id":2,"address":" My address1"}]
var oModel = new sap.ui.model.json.JSONModel("URL");
oModel.attachRequestCompleted(function(data) {
//Print out the json data to the console into a table format using this
console.table(this.oData);
//Update the structure
oModel.setData({modelData: oModel.oData});
//Retrieve individual value direct trough oModel
console.log("Address::"+ oModel.getProperty("/modelData/0/address"));
});