When I try to submit my app with the new seed Xcode 7.1 beta (7B60) I receive a weird error by which it complaints that there is \"No accounts with iTunes connect access - i
I was able to still successfully export the app (rather than clicking upload to app store) and signing still worked. Apple also allows you to use something called the Application Loader. I was able to successfully upload this way.
https://developer.apple.com/library/content/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/UploadingBinariesforanApp.html