Note that, in general, you need to say what the actual problem is that you're experiencing when posting here. See Steps to Reproduce for the kind of description we need.

But assuming you're referring to a file upload failure in the iOS app, try again now. Connections to some Amazon cloud servers are being blocked by your internet connection, and it turns out the workaround we put in place for that a few months ago only applied to the desktop app. We've now changed it to apply to the iOS app as well.