Hi @Godfrey,
You have 3 possible options here:
-
explain the situation to Apple Connect and ask what you should do to " Rebuild your app using the current public (GM) version of Xcode and resubmit it.", as you are already using the last GM.
-
wait for next GM
-
if you have another Mac with XCode installed, try to build and resubmit from there.
Thanks