Thank you for contacting us. Apple have indeed introduced a new requirement in the bundle approval process when uploading your app to iTunes Connect. Info.plist must now contain the following key: CFBundleShortVersionString.
Currently, AppBuilder does not automatically set this key and you need to set it manually as you have already done. We are aware of the issue and we have outlined the steps for manually adding the key in this forum post. We will also make sure to include a fix (to automatically set this key based on the value for Version that you have set in the Project Properties dialog) with our next release.