Mobile responsive dropdown menu not working

I am placing sub items under the parent pages in the navigation bar menu, and on desktop it is working fine. However, on the mobile responsive version I can no longer successfully click the sub items in the dropdown menu. When I click on the parent link a dropdown menu appears with the names of the sub pages, but when I click on the sub pages nothing happens. Everything was working fine last week, so this is a new issue, and only on mobile devices.

Thank you for your help in resolving this!