I uploaded my app to the App Store using xcode. I can see my build in my existing app on iTunes connect. However when I want to add the build using the \"+ Version or platfo
GrangerFX has the answer.
In the App Store click on your app, then the version number under iOS App on left. This will open the Prepare for Submission screen on right (unless you already did that).
Scroll down to "Build" section, and click the "do not enter" sign, which is some secret code that means delete (rather than a typical trash can). [Nice UI Apple! Keep trying, maybe you will get it right one day.]
Then you will be asked to pick a build. Choose your latest uploaded build.