I tried Xcode 16.1 RC1 and can confirm that the issue persists. I figured out how to submit a bug report and my feedback number is FB15618810 We actually have authentication keys set up and I believe it is getting used during the upload process but not the signing / build process. I would have to do some debugging of our Fastlane system to determine whether or not getting it to use the auth key is an easy parameter change or something that would require a lot of work to make work.