Hey Elliot, i have wrote the following code in functions.php, but it doesn’t work.

add_filter('avia_post_nav_categories', 'use_same_category_filter');
    function use_same_category_filter($same_category)
    {
        $same_category = true;
        return $same_category;
    }

I have read that the filter in Enfold has changed a bit (https://kriesi.at/support/topic/avia-post-nav-with-the-same-category-not-work), and so i have wrote the following code in functions.php.
With this function Enfold doesn’t show the arrows to change product, also if there is another product in the same category.

add_filter('avia_post_nav_settings','avia_same_category_filter', 10, 1);
    function avia_same_category_filter($settings) {
        $settings['same_category'] = true;
        return $settings;
    }

thank you
best regards
Salvatore

Thanks for support, it worked!