I just started having the same issue in Xcode 26.6 (17F113). I've logged out deleted and reinstalled the Codex component, and tried logging in; in Xcode Settings > Apple Intelligence, I can log in to "ChatGPT in Xcode", and I can go to "Codex", have it to send me to Safari to log in, successfully log in to OpenAI, and get the "you may now close this window" message, but then Xcode still shows "Not Logged In" for Codex.