So far, I've been able to train a LUIS model and hook up its intents into a dialog that inherits from LuisDialog. I assumed that when whenever I sent an unrecognizable message to the model, it would be captured by the 'None' intent, and that's true for text, but not for files. When i send a picture, for instance, nothing happens, and when I send text+picture, some intent will pick it up, but there will be no picture in the message attachments.
What is the recommended way to handle files inside a LUIS dialog?