makeWebRequest not working on device

I can make simple GET requests with makeWebRequest() to https://captive.apple.com with the simulator however, when I side load the app onto a Garmin VivoActive 3 (SW Version 6.4, Connect IQ 3.0.10) which is connected via bluetooth to an Android version of the Garmin Connect App (version 4.2). The request fails with a response of -400 (INVALID_HTTP_BODY_IN_NETWORK_RESPONSE) and null data. The phone can access https://captive.apple.com via its web browser. Why would this be different on the device and how do I resolve it?

Below is the code:

 using Toybox.System
 using Toybox.Communications

 function onReceive(responseCode, data) {
   if (responseCode == 200) {
     System.println("Request Successful");
     System.println("Response: " + responseCode + " Data: " + data);  

   }
   else {
     System.println("Response: " + responseCode + " Data: " + data);
   }
 }

 function makeRequest(action) {
   var url = "https://captive.apple.com";
   var params = {};
   var options = { // set the options
     :method => Communications.HTTP_REQUEST_METHOD_GET,
     :headers => {
       "Content-Type" => Communications.REQUEST_CONTENT_TYPE_URL_ENCODED},
     :responseType => Communications.HTTP_RESPONSE_CONTENT_TYPE_TEXT_PLAIN
   };

   var responseCallback = method(:onReceive);

   Communications.makeWebRequest(url, params, options, method(:onReceive));
 }

Also, If I change the URL to the non-https version (http://captive.apple.com) on the device I get a -300 (NETWORK_REQUEST_TIMED_OUT) response and null data. Is this due to the watch only allowing the use of HTTPS?

Thanks