When response returned from the xml call, when xmlrpc_decode_request or Zend_XmlRpc_Client of php is used to decode the response to specific object, its not working properly, and returning blank responses without any parameter details

Works just fine here and for other people too so it must be some problem with your installation.

When we tried using the Zend_Xml_Rpc_Client to call it returns the blank array of data when using add_participants, while also tried for the get_participant_details call, it returns array with value but no keys,

Please attach a example code. Thank you.

Please find the below sample code, to test it will just need to install zend libraries via composer, and run below code.

<?php
require 'vendor/autoload.php';

use Zend\XmlRpc\Client;

$surveyId = 668645;

$client = new Client('http://www.limesurvey.rak/index.php/admin/remotecontrol');

$sessionKey = $client->call('get_session_key',array('admin','g5gefgrtRRR'));

$participant_data = array('participantData'=>array('firstname'=>'ravindra','lastname'=>'khokharia','email'=>'ravindra.khokharia@tts-talent.com','language'=>'en'));

$response = $client->call('add_participants',array($sessionKey,$surveyId,$participant_data));

var_dump($response);

Added fix for the issue, and pull request,
Please go through, if ok then please do accept and merge pull request

https://github.com/LimeSurvey/LimeSurvey/pull/185

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=14070

2.05+ Build 140404 released.