Channel message handler not getting triggered in section page

I am calling business process from contact section to run a script task to send a message from server to the page. Based on the message, 

I am trying to display browser notification message. I am facing following issues:

• Sometimes browser notification message is not being displayed at all or only business process notification ("service is started ") is displayed
• Often onMessageReceived method is not getting triggered at all despite user task running successfully

kindly help in resolving the issue. Refer below for code

//user task code in business process
	var UImessage = JsonConvert.SerializeObject(new
                {
 
                    Message = "Please try again later"
                }
             );
            //intendedUserId is unique identifier parameter sent to business process(current user login)
            var intendedUserId = Get<Guid>("intendedUserId");
 
            IMsgChannel channel = MsgChannelManager.Instance.FindItemByUId(intendedUserId);
            if (channel != null)
            {
                var simpleMessage = new SimpleMessage()
                {
                    Id = intendedUserId,
                    Body = UImessage,
                    Header =
                        {
                         Sender = "BrowserNotification"
                        }
                };
                channel.PostMessage(simpleMessage);
            }
 
 
	return true;

//section page
define("ContactSectionV2", ["DesktopPopupNotification","ProcessModuleUtilities"], function(DesktopPopupNotification,ProcessModuleUtilities) {
	return {
 
		methods: {
			init: function(){
				this.callParent(arguments);
				this.Terrasoft.ServerChannel.on(Terrasoft.EventName.ON_MESSAGE,
				this.onMessageReceived, this);
 
				if (DesktopPopupNotification.getPermissionLevel() !== DesktopPopupNotification.PermissionType.GRANTED) {
					DesktopPopupNotification.requestPermission(); 
 
				}
				//process that runs user task
				this.callCustomProcess();
 
			},
			onMessageReceived: function (sender, message) {
 
				if (message.Header.Sender === "BrowserNotification") 
				{
                  this.console.log("message");
					if (DesktopPopupNotification.getPermissionLevel() !== DesktopPopupNotification.PermissionType.GRANTED) 						{
                      	this.console.log("no permisssion");
                    		return; 
                		}
 
                        var config = {
                            id: 123456,
                            title: "Test notification",
                            body: "This is a test notification",
                            icon: Terrasoft.ImageUrlBuilder.getUrl(this.get("Resources.Images.UsrIcon")),
                            onClick: this.onDesktopNotificationClick,
                            ignorePageVisibility: true,
                            timeout: 5000,
                            scope: this
                        };
					this.console.log("displaying message");
					DesktopPopupNotification.showNotification(config);
				}
 
 
			},
			callCustomProcess: function() {
				var args = {
					// Process name
					sysProcessName: "UsrProcess_05207ff",
					// parameters process
					parameters: {
						UsrLeaveRequestID: parameter
					}
				};
				// run process
				ProcessModuleUtilities.executeProcess(args);
			},
			destroy: function() {
						this.Terrasoft.ServerChannel.un(Terrasoft.EventName.ON_MESSAGE, this.onMessageReceived, this);
						this.callParent(arguments);
			}
        }
	}