Hi @radirot
I’m not sure why it isn’t working, but you can always use acf/load_value and str_replace to change that tags automatically for WYSIWYG custom field. You can use this code to do it:
function my_acf_load_value( $value, $post_id, $field )
{
// run the_content filter on all textarea values
$value = apply_filters('the_content',$value);
$value = str_replace("<!--more-->", '<span id="more-'. $post_id .'"></span>', $value);
return $value;
}
add_filter('acf/load_value/type=wysiwyg', 'my_acf_load_value', 10, 3);
I hope this helps.