I’ve been submitting my app to the App Store for test flight and after build 11, I’ve been getting failures via email from Apple:
Non-public API usage: The app conta
I had this exact problem. I was using CommonCrypto as a 'fake' framework. I removed that, and switched to the method described by the accepted answer in this thread, and iTunesConnect accepted my build.
Getting a Swift 4 conversion warning by XCode or having "CommonCryptoModule" showing up in cmd output when using pod update seems to be a strong indicator whether you are affected by this issue or not.