Vertical Scrolling breaks if I confirm rather than timeout

[geoff-maddock]

I'm using sweet alert to generate flash modals after a successful action.
If I let the modal clear after the timer, the vertical scrolling on the page returns. However, if I click the [OK] confirm before the timer runs out, I can't vertically scroll.

    <script>
    swal({
      title: "{{ session('flash_message.title') }}",
      text: "{!! session('flash_message.message') !!}",
      type: "{{ session('flash_message.level') }}",
      timer: 1700,
        showConfirmButton: true,
        closeOnConfirm: true,
    });
    </script>

Is there any config that can fix this?