The data migrated from your source site can be displayed on the new one improperly or not displayed at all due to the peculiarities of your new CMS platform. Also, if your website uses custom theme or template, CMS2CMS doesn’t guarantee proper data presentation after the migration.
However, although content is not visible on the front-end of your site, it is presented in the back-end. It may require certain settings or configurations to make it visible on the front-end.