The menu image with the 3 bars appears in place of the navigation bar, but when clicked, nothing happens. The link at the bottom of the browser shows #mobile-menu, and the button highlights, but when clicked nothing at all happens.
I see you are using a plugin called “Contact Bank” (https://wordpress.org/plugins/contact-bank/) and this plugin has conflicting with theme stylesheet since they do not point directly CSS code to plugin related things but their code point some CSS code to Agama Pro mobile menu styling.
Try disabling that plugin and test if Mobile Menu works ok.
You will also need to contact a plugin author to make proper changes to their plugin CSS to not point a theme related things.