Next-Previous Custom Post type in same Category

Hi,
I followed this post to add a custom post type: https://kriesi.at/support/topic/procedure-for-adding-custom-post-type-and-enabling-it-for-use/

Posts are not made in Avia builder and I have to categories: Lopende projecten and opgeleverde projecten.

When using the next and previous buttons on a post I would like the next or previous post to be from the same categorie.

I searched the forum and found a lot of solutions, all codes below I have tried but non is working.

What can I do to get it working in the same categorie.

url: http://bloemfontein.nl/nw16/projecten/lopende-projecten/ and http://bloemfontein.nl/nw16/projecten/opgeleverde-projecten/
I am using a Child theme

Thanks in advance.

Codes used:
With this one the buttons dissappear

add_filter( 'avia_post_nav_settings', 'enfold_customization_same_cat' );
function enfold_customization_same_cat( $s ) {
	$s['same_category'] = true;
	return $s;
}

This one also the buttons dissappear

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

This one doesn’t work at all

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

This one doesn’t work and the previous button is pointing to the same post as where you are:

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