is it still the same code for 4.5.6 or has something changed on that?
add_filter( 'avia_post_nav_entries', 'enfold_customization_postnav', 10, 2);
function enfold_customization_postnav($entries, $settings) {
$entries['prev'] = get_next_post($settings['same_category'], $settings['excluded_terms'], $settings['taxonomy']);
$entries['next'] = get_previous_post($settings['same_category'], $settings['excluded_terms'], $settings['taxonomy']);
return $entries;
}