I have test your site and noticed that the mobile menu is not working in the window screens when we resize the window and goes to mobile layout.
But on the actual mobile devices the menu works just fine as expected. You need to disable all third party plugins(if you have any) and switch to parent version of theme, also undo your custom code and then check back your site after clearing your site and browser cache. This will surely fix the issue.
In case if it still not working then remain the plugins as disabled and provide me your admin login credentials so I will test with theme default plugins and help you out.
This only works from the home page, once you go to another page the mobile menus do not work!
We do not have any custom code on the site.
How do i switch to the base version of the theme and if i do so will i see any changes on the site theme/pages?
If you are using child version and want to switch to parent version of theme. You can do it from Appearance >> Themes. You will see changes after switching the theme to parent version.
In case after doing this if the problem is not resolved. Then deactivate all of your third party plugins and share your admin login credentials and allow me to troubleshoot your site with theme default plugins.