When I try to submit to TestFlight, I'm told:
"Unsupported SDK or Xcode version ... You need to use the latest Release Candidates for SDKs and Xcode."
I am using the latest Xcode RC, Version 16.3 (16E137). But my guess is that I am not being given, in conjunction with this, the latest iOS 18.4 RC. I need 22E239 but I'm unable to download and install it thru Xcode. What I'm being given is SDK version 18.4 (22E235).