A fix for Polylang language switcher links pointing at front page on post type archives of untranslated post types (Wordpress + Polylang)

functions.php

function polylang_languageswitcher_untranslated_pts_archives_links_fix( $url, $slug ) {

  if ( is_post_type_archive( array('event', 'career') ) ) {
    $url = add_query_arg(
      array(
        'post_type' => get_post_type(), 
      ),
      pll_home_url( $slug )
    );
  }

  return $url;
}

add_filter( 'pll_the_language_link', 'polylang_languageswitcher_untranslated_pts_archives_links_fix', 10, 2 );