Add Custom label in Batch Sidebar on Seats Full.

functions.php

add_action('wplms_batches_extras',function($batch_id){
			$enable_seats = groups_get_groupmeta($batch_id,'enable_seats');
			if(!empty($enable_seats)){
        $count = groups_get_total_member_count($batch_id);
				$batch_seats = groups_get_groupmeta($batch_id,'batch_seats');
        if($count >= $batch_seats){
           echo '<a href="URL_TO_CONTACT_PAGE" class="full">'.__('Waiting','wplms-batches').'</a>';
        }
			}
      
},10,1);