This code works with bootstrap 2, and fixes the show/hide behavior experienced with Respondo if following normal Bootstrap documentation

bootstrap-2-modal.php

# Trigger button/link
# Must use the 'onClick' method to target the modal, rather than 'data-target'
<a href="javascript:void(0);" id="login-pop-trigger" onClick="jQuery(\'#login-popup\').modal();" role="button" data-toggle="modal"><i class="fas fa-user-plus" aria-hidden="true"></i> Login</a>

# Simple Modal
<div id="login-popup" class="modal fade" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true" style="display: none;">
  <div class="modal-body">
        <p>You are about to delete this Page, this is irreversible.</p>
    </div>
</div>