UWP FileOpenPicker locks\freezes app in debug - windows

Question

If the debugger is attached, calling this function causes the app to hang. If I run without a debugger, there is no hang, and file pickers work perfectly.
private async void OnClick(object sender, RoutedEventArgs e)
{
FileOpenPicker openPicker = new FileOpenPicker();
}
I'm certain this is something super simple, but I just don't know.
Edit:
Here's how I'm using it. Keep in mind, that the simpler function creates the hang issue without all my extra code after it. I've stuffed up the image saving, but that's a separate issue I want to debug when I solve what this post is about.
.
public async Task ImportHeader()
{
FileOpenPicker openPicker = new FileOpenPicker();
openPicker.ViewMode = PickerViewMode.Thumbnail;
openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
openPicker.FileTypeFilter.Add(".jpg");
openPicker.FileTypeFilter.Add(".png");
// For multiple image selection
var files = await openPicker.PickMultipleFilesAsync();
foreach (StorageFile singleImage in files)
{
IRandomAccessStream stream = await singleImage.OpenAsync(Windows.Storage.FileAccessMode.Read);
var image = new BitmapImage();
image.SetSource(stream);
HeaderImage.Source = image;
//We also save this to disk for later
Windows.Storage.StorageFolder storageFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
Windows.Storage.StorageFile file = await storageFolder.CreateFileAsync("header.jpg", Windows.Storage.CreationCollisionOption.ReplaceExisting);
stream.Seek(0);
using (StreamWriter bw = new StreamWriter(file.OpenStreamForWriteAsync().Result))
{
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, stream);
var renderTargetBitmap = new RenderTargetBitmap();
await renderTargetBitmap.RenderAsync(HeaderImage, (int)HeaderImage.Width, (int)HeaderImage.Height);
var pixels = await renderTargetBitmap.GetPixelsAsync();
byte[] bytes = pixels.ToArray();
bw.Write(stream);
}
}
}

Answer 1

This has happened to me as well on some of the recent Windows 10 Insider Preview builds, while the process works flawlessly on stable builds of Windows 10. I think you can assume the cause is there instead of your code.