Page_Load is not processing after async method obtains the required value - asynchronous

Question

I have a page load that I am having difficulty with getting it to obtain a value from an async button click. The code is below. I am very new to this so please take that into consideration. What happens is essentially the code seems to just stop after the button is clicked and the GetAuthorizationCode executes. I get the value back on the temp Response in getReportButton_Click, but no other methods are executed on the Page_Load section. Essentially, I had this working in an older version of the Microsoft.Identity reference, but after upgrading it required switching many components to async and that is where I am stuck now.
protected void Page_Load(object sender, EventArgs e)
{
if (Request.Params.Get("code") != null)
{
Session["AccessToken"] = GetAccessToken();
Response.Redirect("/Default.aspx");
}
if (Session["AccessToken"] != null)
{
accessToken.Value = Session["AccessToken"].ToString();
GetReport(0);
}
}
protected async void getReportButton_Click(object sender, EventArgs e)
{
var temp = await GetAuthorizationCode();
Response.Write(temp);
}
public async Task<string> GetAuthorizationCode()
{
var serviceUri = "XXXXXXXX";
var clientID = "XXXXXXXXX";
var userName = $"XXXXXXXX";
var password = "XXXXXXXXX";
using (var webClient = new WebClient())
{
var requestParameters = new NameValueCollection();
requestParameters.Add("resource", serviceUri);
requestParameters.Add("client_id", clientID);
requestParameters.Add("grant_type", "password");
requestParameters.Add("username", userName);
requestParameters.Add("password", password);
requestParameters.Add("scope", "openid");
var url = $"XXXXXXXXXXXX";
var responsebytes = await webClient.UploadValuesTaskAsync(url, "POST", requestParameters);
var responsebody = Encoding.UTF8.GetString(responsebytes);
return responsebody;
}
}

Answer 1

I ended up changing multiple aspects of this code to the point the original post isn't close to the ending code. Log story short, I pulled the GetAuthorizationCode() under the button click and moved it to the page_load, storing the output to a global variable. I then pass that global variable to the button click action to call the other async tasks.