Ubuntu Not Quite Perfect

The user accounts Ubuntu said it was migrating, it didn’t. The Firefox settings for the one account I set up were moved, but none of the other user accounts got moved. Worse, when I tried to add them, the “Add User” button is greyed out. Even when I did sudo users-admin I can’t add users.
[update: Seems you need to click “unlock” on the GUI to enable adding accounts.]