Hi there, I’ve just found a link to your site in the bounced emails so took a look. I can see in the source code there are no links being provided in the mobile menu for the drop down, just the word ‘menu’. I’ve checked the settings in the appearance > menu tab and they are showing the mobile option as checked, so I would strongly assume this is down to the caching that wp-engine has in place. I would advise talking to them to find out how you can clear the cache fully to get the 100% live site.
I will drop a message to the Dev team as well in the meantime to see if they can think of anything else other than the cache which could affect the menu. It is still showing you’re using version 5.4 of the theme, I’d advise upgrading to 5.5 to make sure its on the latest version.