I had to go to "Preferences" -> "Accounts", where it turned out my Apple ID had timed-out. After logging-in there, and then restarting Xcode, my profile was automatically "repaired", and all is now well.
I had to go to "Preferences" -> "Accounts", where it turned out my Apple ID had timed-out. After logging-in there, and then restarting Xcode, my profile was automatically "repaired", and all is now well.