Async/ConfigureAwait(True) does not wait - WebService - vb.net

Question

I have a webservice GetCard which calls a function CreateRaces. Inside the CreateRaces I am saving the new objects. This works fine without async. However, when I call the async function for task1 CommitAsync the method executes and returns a response without hitting the next break point. I have tried to work around with via Task.Run, ConfigureWait(true), and with
With HttpContext.Current
bulk.Setup etc...
End With
but nothing seems to work.
The bulk.Setup - CommitAsync calls a third party dll (SqlBulkTools) which returns Task.
It looks like it works on a different thread.
Any ideas how to configure it so I the function executes and I can hit the next break point which is sw.Stop()?
<HttpGet>
<AllowAnonymous>
Public Async Function GetCard(cardurl As String) As HttpResponseMessage
Try
Dim oRace As New RaceCard(cardurl)
oRace.DoWork()
Dim oRC As New RaceController
await oRC.CreateRaces(oRace.Races)
Return Request.CreateResponse(HttpStatusCode.OK, True.ToJson)
Catch ex As Exception
Return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, ex)
End Try
End Function
CreateRaces function
Public Async Function CreateRaces(ByVal t As List(Of Race)) As Threading.Tasks.Task(Of Boolean)
Try
'Proceed only if list has items
If t.Count > 0 Then
Dim bulk As New BulkOperations()
Dim sw As New Stopwatch()
Dim oCon As New SqlClient.SqlConnection(DotNetNuke.Common.Utilities.Config.GetConnectionString)
sw.Start()
Dim task1 = Await bulk.Setup(Of Race).ForCollection(t).WithTable("ArbiRace").AddAllColumns().BulkInsertOrUpdate().SetIdentityColumn(Function(i) i.RaceID).MatchTargetOn(Function(m) m.RaceName).CommitAsync(oCon).ConfigureAwait(True)
sw.Stop()
Dim swt = sw.ElapsedMilliseconds
End If
Return True
Catch ex As Exception
Dim s As String
s = ex.ToString
Return False
End Try
End Function

Answer 1

Asnyc calls can be handled in 2 ways:
Deliberately halting thread execution until one, several, or all tasks are completed.
Leaving the task to run while the current thread goes to do something else.
Based on your question, you are expecting #1, but your code currently does #2. Await Documentation:
An Await expression or statement does not block the thread on which it is executing. Instead, it causes the compiler to sign up the rest of the async method, after the Await expression, as a continuation on the awaited task. Control then returns to the caller of the async method. When the task completes, it invokes its continuation, and execution of the async method resumes where it left off.
In your case, once CreateRaces() reaches the Dim task1 line (which will eventually store the result, not the task), control returns to GetCard(). However, the CreateRaces() call here also uses an Await, so control attempts to go back up the call stack again. Except, there is nowhere left to go up, because you are at the original endpoint. This is why you seem to get a response too soon.
Since you are waiting for the task to finish to get the elapsed time, you want to wait for the tasks to finish before returning a response. This can be accomplished with task.Result, task.Wait(), or the shared method Task.WaitAll().
Example:
<HttpGet>
<AllowAnonymous>
Public Function GetCard(ByVal cardUrl As String) As HttpResponseMessage
Try
Dim oRace As New RaceCard(cardurl)
oRace.DoWork()
Dim oRC As New RaceController
Dim createRacesTask As Threading.Tasks.Task(Of Boolean) = oRC.CreateRaces(oRace.Races)
'Do other tasks here while we wait
Threading.Tasks.Task.WaitAll(createRacesTask, ...)
Return Request.CreateResponse(HttpStatusCode.OK, True.ToJson)
Catch ex As Exception
Return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, ex)
End Try
End Function