Exclude elements from sitemaps

Hello,

I tried to exclude an array of elements from the sitemap.
Benjamin Denis directed me to the filter seopress_sitemaps_term_single_query bit I can’t make it work.

I understood that if modifies the default arguments for the query, so I tried this, without any effect :

function test_seop_exclude_from_sitemap ( $args, $tax ) {
    $args['exclude'] = array(155,987) ;
    return $args ;
    }
add_filter('seopress_sitemaps_term_single_query', 'test_seop_exclude_from_sitemap', 10, 2);

the two terms are still in the sitemap

So I went to something even simpler :

function test_seop_exclude_from_sitemap ( $args, $tax ) {
    $args['number'] = 10 ;
    return $args ;
    }
add_filter('seopress_sitemaps_term_single_query', 'test_seop_exclude_from_sitemap', 10, 2);

I expected to have only 10 terms in my sitemap, and I have all 170.

What am I doing wrong ?