Version 1.2.3 has just been released, this update fixes an issue introduced in version 1.2.0. In version 1.2.0 when you edit and save a default required field ( example: the user email field ), the field would set itself as non-required and cannot be set as required again.
The issue has now been fixed, please update the plugin to version 1.2.3. After the update, you should see a notification into your dashboard asking to upgrade the fields. Press the upgrade button and all the default required fields will be fixed automatically.
If the notice does not appear, you can manually force the upgrade by adding index.php?wpum_upgrade=121 to your wp-admin address.
Example: if your site address is http://mysite.com add this (without quotes) at the end of the url /wp-admin/index.php?wpum_upgrade=121/
So the address will be http://mysite-com/wp-admin/index.php?wpum_upgrade=121