makeWebRequest does not execute callback on device

The following makewebrequest code is successfully working in the simulator. However, when sideloaded to the device (vivoactove 4S), the callback is never executed.

var url = Application.Properties.getValue("API_URL");
url += "/rest/getPlaylist";
var usr = Application.Properties.getValue("API_usr");
var key = Application.Properties.getValue("API_key");

var params = {
	"u" => usr,
	"p" => key,
	"f" => "json",
	"id" => "1"
};
var options = {
	:method => Communications.HTTP_REQUEST_METHOD_GET,
	:responseType => Communications.HTTP_RESPONSE_CONTENT_TYPE_JSON
};
Communications.makeWebRequest(url, params, {}, method(:onGetPlaylist));

Are there additional requirements on this web request when it is running on a physical device? The project is an audio content provider app and the code above is executed in the ConfigureSyncView class onShow method. The project was created from the template for audio content provider apps.