<form id="#form1" method="get" action="http://localhost:/learndash3/chain-announcements">

<?php echo $_SERVER['PHP_SELF']; ?>

<button type="submit" name="submit" class="btnadd">AddSelected</button>

<?php

        if (isset($_GET['submit'])) {
        $checked = $_GET['item'];
        if($checked !=""){$checked_string = implode(" ",$checked);
       update_user_meta( $current_user->ID, 'archived_announcements', checked_string);
        //echo '<META HTTP-EQUIV=Refresh CONTENT="0;   URL='.$current_URL.'">';
        echo $checked_string;
        }else{
        echo "nothing selected";
        }
        }
        ?>