I am also experiencing this same issue. I am using 4.21 and Xcode 10.1 (Apple requires you do have xcode 10.1 as of march 1st to upload to app store/test flight).
I am also experiencing this same issue. I am using 4.21 and Xcode 10.1 (Apple requires you do have xcode 10.1 as of march 1st to upload to app store/test flight).