What causes the 'Invalid File' to display on the initial screen of the prototype before it launches.  I have noticed it on a few of my prototypes and I'm not sure what the cause is, because if you continue and launch the prototype it resolves itself and works, but the initial screen tends to scare other users when they go to look at it and they think it is broken.  I am not sure how to figure out what invalid content is in the prototype itself.  I have attached an image of what I'm talking about.  Also I am on 2017 Vol.2 (Update 2.2).