If the dropdown icon is not working, add the following to Divi > Theme Options > General > Custom CSS:

#top-menu .menu-item-has-children>a:first-child:after, #main-header .et_mobile_menu .menu-item-has-children>a:after { content: '\e04c'; }

#main-header .et_mobile_menu .menu-item-has-children.visible>a:after { content: '\e04b'; }