That looks like a custom post type.
If it was added by the previous theme, then it won’t be in GeneratePress.
This is something theme developers call “theme lock”. Themes shouldn’t add custom post types, they should have handled by plugins so themes can be easily changed.
You can try adding this custom post type yourself. This plugin might help: https://en-ca.wordpress.org/plugins/custom-post-type-ui/
You would just need to name it the exact same: