try this function in your functions.php file and then add the name of your CPT to the title tag of the menu item in your menu. So web CPT title = web.
// setup proper class for custom post type menu items based on the menus title tag
function current_type_nav_class($classes, $item) {
$post_type = get_query_var('post_type');
if ($item->attr_title != '' && $item->attr_title == $post_type) {
array_push($classes, 'current-menu-item');
};
return $classes;
}
add_filter('nav_menu_css_class', 'current_type_nav_class', 10, 2 );
Then use the css class of current-menu-item to highlight it correctly.