Works for me with my Plus account, but not with my Pro account. At some point, I had run "sudo xcode-select -s /Applications/Xcode.app/Contents/Developer" from one of the posts above, not sure if that helped. "xcrun agent codex login" works with both accounts on the terminal. When using that to log in with my Plus account, I am logged in in Xcode, Codex is usable there. With my Pro account, I am logged out in the Xcode UI (but "xcrun agent codex" works fine on the terminal) This must be an UI integration issue in Xcode. Slightly off-topic: why must I use Safari to post this? In Chrome, I don't even get this reply field, even though I am logged in. Apple disappoints more and more :(