Category and subcategory = page not found

Dear,

I have a problem with my category pages with polylang.
I have 2 languages : english and french. I have a category artist (fr: artiste) and three articles inside.
In french, everything works. If i go on mywebsite.ch/fr/artiste/my-article-in-french it works as well as if i go
in english mywebsite.ch/en/artist/my-samed-article-in-english.

But if i go to mywebsite.ch/en/artist/ i get a page not found.

I tried with my custom post types and others taxinomies too. I get this problem only with the Categories.
I cannot show any page with categories and sub-categories in english. It works only in french.

As i have some custom post type shown in the category gallery, i have this code :
I thougth maybe it could cause a problem, i removed it but nothing change.

add_action('pre_get_posts', 'add_my_custom_post_type');

function add_my_custom_post_type($query) {
	if ( ! is_admin() ) {
		 if(
        empty($query->query['post_type'])
        or $query->query['post_type'] === 'post'
    ){
        $query->set('post_type', array('page','post', 'oeuvre', 'events'));
    }
	}else{
		 if(
        empty($query->query['post_type'])
        or $query->query['post_type'] === 'post'
    ){
        $query->set('post_type', array('post'));
    }
	}
} 

If someone has any idea… would be helpfull !
I use polylang on several websites and it’s the first time i get this problem.

Thank you verry much!