Winform AllowDrop not working when debugging

Question

I have a small and simple Winform app which contains a Textbox with the AllowDrop property set to true. I'm handling the DragDrop and DragEnter events as such:

Private Sub txtFile_DragEnter(sender As Object, e As DragEventArgs) Handles txtFile.DragEnter
    If e.Data.GetDataPresent(DataFormats.FileDrop) Then
        e.Effect = DragDropEffects.Copy
    End If
End Sub

Private Sub txtFile_DragDrop(sender As System.Object, e As System.Windows.Forms.DragEventArgs) Handles txtFile.DragDrop
    Dim files() As String = e.Data.GetData(DataFormats.FileDrop)
    If Not files Is Nothing AndAlso files.Length > 0 Then
        txtFile.Text = files.First()
    End If
End Sub

The problem I'm having is that the textbox will not accept a file drop when I F5 debug, instead I get the 'No' cursor. If I end debugging and run the executable from the /bin folder, it works as expected.

Is there something specific about Visual Studio debugging which would prevent filedrops from working, or do I need to change any code for debugging?