As stated here, the featured box does not work with Polylang.
The problem seems to be localized in the function “cryout_localize_cat” in file wp-content/themes/fluida/cryout/prototypes.php (line 1073 in Fluida 18.104.22.168)
The get_term_by function is filtered by current language. To retrieve the category in any language, the get_terms function with the empty string assigned to the ‘lang’ argument must be used.
So one workaround is: $cat = get_terms(array('taxonomy' => $tax, 'slug' => esc_attr($slug), 'lang' => ''));
instead of $cat = get_term_by( 'slug', esc_attr($slug), $tax );
It works as expected with Polylang and 2 languages.