'Close' and 'Save' button in the modal not working after I add another modal in the same html page

After adding the second modal to the same html page, 'Save' and 'Close' buttons in the first modal stopped working. I tried to remove fade class, but it did not help. Please help. If I remove class="modal fade"

Modal 1

<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria- 
labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog modal-lg">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="0">Modify Job Details for:</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body row">
        <div class="ui vertical steps col-sm-6">             
        </div> 
      </div>
      <p id="signatureWarning" class="alert alert-danger" role="alert"></p>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button id='modify-complete' type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

Modal 2

<div class="modal fade" id="invoiceModal" tabindex="-1" role="dialog" aria-labelledby="invoiceModalLabel"
  aria-hidden="true">
  <div class="modal-dialog modal-lg">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="invoiceModalLabel">Invoice the Customer</h5>
        <button type="button" class="close" onclick="$('#invoiceModal').modal('hide')" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>   
      <div class="containerInvoice">
        <div class="modal-body row">    
        <div>          
      </div> 
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button id='invoice_button' type="button" class="btn btn-primary">Generate Invoice</button>
      </div>
    </div>
  </div>
</div>