do you have the latest application loader. you may need to update it to the latest version.
I've tried with 3.4 and doesn't work, In my version for development there's a gray row on the top of the screen, it's strange. It seems that Phonegap Build has some problems building the ipa
what version of xcode do you have?
Ihave this problem too.
Version of my Enviroment:
Application Loader 3.4
Since April 1st, it's mandatory to use Xcode 9 to submit apps
I have just successfully used Application Loader 3.6 to submit an app built by PGB.