custom post type Search returns No Results in admin panel

For the Post table Search option, It will check with post titles. Not the whole table like what you can do it on jQuery DataTable. So, this options is not supported in default. But I found some code for you to work on, I didn’t try the code, check it on your own risk.

function cf_search_join( $join ) {
    global $wpdb;

    if ( is_search() ) {    
        $join .=' LEFT JOIN '.$wpdb->postmeta. ' ON '. $wpdb->posts . '.ID = ' . $wpdb->postmeta . '.post_id ';
    }

    return $join;
}
add_filter('posts_join', 'cf_search_join' );

function cf_search_where( $where ) {
  global $pagenow, $wpdb;

   if ( is_search() ) {
      $where = preg_replace(
        "/\(\s*".$wpdb->posts.".post_title\s+LIKE\s*(\'[^\']+\')\s*\)/",
        "(".$wpdb->posts.".post_title LIKE $1) OR (".$wpdb->postmeta.".meta_value LIKE $1)", $where );
    }

   return $where;
   }
 add_filter( 'posts_where', 'cf_search_where' );


 function cf_search_distinct( $where ) {
   global $wpdb;

    if ( is_search() ) {
        return "DISTINCT";
   }

   return $where;
 }
 add_filter( 'posts_distinct', 'cf_search_distinct' );

try and if you have any problem check here. for more details.
Here