If we comment out the call to StorageItemContentProperties::GetImagePropertiesAsync, then we don't get the crash. But the real fix is to make the StorageFile.GetThumbnailAsync call be explicitly async by cooperatively awaiting wil::resume_foreground immediately before calling GetThumbnailAsync. This works because wil::resume_foreground schedules the code that follows it to be a task on the DispatcherQueue.