Custom Fields Import

What is the catch to importing custom fields?
All fields are created with the key that corresponds to the ones inside import settings page Custom fields Section. They are connected to the values from the csv file. However, they are not created or updated by the import. I do not want to buy ACF addon or Pro version since this functionality is listed here in the Free version.
Import data to Custom Fields – used by many themes, especially those using Custom Post Types – to store data associated with the posts.

Am I missing something? How can I make this work?