SendGrid Marketing Email Delay?

Steps

1. Create recipient list
2. Create marketing Email
3. Add emails to recipient list
4. Assign recipient list to marketing email

When I debug slowly, i managed to passed all steps with success message from sendgrid.

But in non debug mode, although i added emails to recipient list success(results return from sendgrid), when in step 4, i get results return List without recipients. I refresh the browser and saw the emails in the recipient list as well.

I tried to put timer.interval before start to process step 4 but also get the same results return.

VB ProcessHandler Code

' Add email and name to recipient list 
 If oSendMarketingEmail.AddEmailToList(oItemDetails.Email, oItemDetails.Full_Name, sRecipientList) = False Then Exit Try

' Wait for the email and name added to recipient list
 Dim timer As New Timers.Timer
 timer.Interval = 20000

 ' Assigning recipient list to marketing email
  If oSendMarketingEmail.AddListToMarketingEmail(sMarketingEmailName, sRecipientList) = False Then Exit Try

VB Function Code

    Public Function AddEmailToList(sEmailAddress As String, sName As String, sRecipientList As String) As Boolean

        Dim ResultsHTML As String = ""

        Dim URL As String = (Convert.ToString("http://sendgrid.com/api/newsletter/lists/email/add.xml?list=") & sRecipientList) + "&data=" + "{""email"":""" + sEmailAddress + """,""name"":""" + sName + """}" + "&api_user=" + SendGridUserName + "&api_key=" + SendGridPassword
        Dim SendGridResponse As String = PerformHTTPGet(URL)
        ResultsHTML += (Convert.ToString("Adding email to List: ") & SendGridResponse) + "<br/>"

        ' Check respond status - success
        If Not ResultsHTML.Contains("insert") Then logger.log.Info(ResultsHTML) : Return False Else Return True

    End Function


    Public Function AddListToMarketingEmail(sMarketingEmailName As String, sRecipientList As String) As Boolean

        Dim ResultsHTML As String = ""

        'Assign list to marketing email
        Dim URL As String = (Convert.ToString((Convert.ToString("http://sendgrid.com/api/newsletter/recipients/add.xml?name=") & sMarketingEmailName) + "&list=") & sRecipientList) + "&api_user=" + SendGridUserName + "&api_key=" + SendGridPassword
        Dim SendGridResponse As String = PerformHTTPGet(URL)
        ResultsHTML += (Convert.ToString("Assigning Marketing Email to List: ") & SendGridResponse) + "<br/>"

        ' Check respond status - success
        If Not ResultsHTML.Contains("success") Then logger.log.Info(ResultsHTML) : Return False

    End Function

In SendGrid, the list-count can take a little while to update. One way to "force" it is to query the full list, which triggers the system to count through, and will update the count, which will then allow you to attach it properly.