Lambda function not executing http.get

I have a function that when tested locally worked fine, but when running via AWS Lambda doesn't seem to execute the HTTP get. The code is as follows:

function makeAPIRequest(path, responseControl, callback) {

    var responseString = '';
    console.log("Executing makeAPIRequest to " + apiSettings.host + " and path " + path);
    var options = {
        host: apiSettings.host,
        path: path,
        method: 'GET',
        headers: {
            'X-Auth-Token': apiSettings.token
        }
    };
    http.get(options, function (res) {
        console.log('Status Code: ' + res.statusCode);
        if (res.statusCode != 200) {
            callback(new Error("Non 200 Response"));
        }
        res.on('data', function (data) {
            responseString += data;
        });
        res.on('end', function () {
            console.log('http end function hit...');
            callback(null, responseString);
        });
    }).on('error', function (e) {
        console.log("Communications error: " + e.message);
        callback(new Error(e.message));
    });
}

I initially wrote it using the request npm package but that failed, so I dropped back to vanilla http.get, but neither seems to execute. In the log output from Lambda I can see the output of the following:

console.log("Executing makeAPIRequest to " + apiSettings.host + " and path " + path);

with the correct host and path being passed in, but

console.log('Status Code: ' + res.statusCode);

never outputs to the screen. There are no errors logged and the API endpoint that I'm hitting reports the number of API requests, but this isn't changing, so I dont think the request is even being made.

Has anyone got Lambda to make http calls and if so, any ideas on what I'm not doing here?

Thanks

Edit: verified that 'no vpc' is set in the advanced settings section of lambda