Common IssuesContent in Gutenberg post is not translated
Content in Gutenberg post is not translated
If the content of a Gutenberg custom post is not translated, while the title is translated, then most likely you have a Page Builder installed on your site (Elementor, Bricks, etc) and that CPT is assigned to the Page Builder.
As such, Gato AI Translations will attempt to translate that post's content as pertaining to that Page Builder, not to Gutenberg.
Solution: Remove that CPT from being handled by that Page Builder via its Settings page. (Then it'll be handled by Gutenberg, and the plugin can translate it.)