Responsive Menu Doesn't Respond

I am running the following versions of things: WordPress Version: 5.1 Catch Base Pro Theme: 3.7.2 PHP Version: 7.0.33 The menu stops working on the mobile version on the iPhone or whenever the screen is small enough to show the "hamburger" menu. So does the “Return to Top” button Here’s what happens. Upon opening Safari and going to the website URL (https://www.everygoodgift.org), the top-line menu is available and functions, but after a couple of uses to go to other pages on the site, the “Return to Top” button disappears and the menu no longer works. Clicking on it no longer opens the full menu on the left. Instead it simple refreshes the current page.