This feels like an iTunes Connect bug, but maybe I'm doing something wrong. I'm trying to create auto-renewing subscription in app purchase items for my Mac app to start testing the subscription sign up flow in my app.I've created an app in iTunes Connect. In the Features tab I've created various in-app-purchase items with different prices and duration in a single subscription group. So far so good.I filled out all the required information, but all of my items are stuck in the "Missing Metadata" state, so I don't appear to be able to test them yet. The only thing I haven't filled entered is a screenshot and review description (why those would be needed for testing since they are review related, I'll never know).However, when I try to upload a screenshot, it appears to be impossible. The help text says "We’ll only use the screenshot for our review—it will not be displayed on the App store. Screenshots must have valid dimensions for your app platforms." However, it unhelpfully doesn't specify the resolution I need. If I try to upload any image, I get an invalid size error and it tells me it must be 640x920 (seems suspiciously like an iOS resolution, not an OS X resolution...).When I try to upload a screenshot from my app with a 640x920, it works, but when I hit save I get the following error:"You must upload a valid screenshot."There is no indication of what constitues a valid screenshot or what was wrong with the screenshot I used.Two questions for anyone that may know the answer:1. Is a screenshot necessary for testing or am I in the metadata missing state for some other reason?2. Is this a bug in iTunes Connect?Right now this is completely stopping me from doing any subscription testing, so it's very frustrating.