fix

lib/web/jquery/ui-modules/menu.js

@@ -453,11 +453,14 @@ define([
                 .hide()
                 .attr("aria-hidden", "true");
 
+            submenu.parent().parent()
+                .show()
+                .removeAttr("aria-hidden")
+                .attr("aria-expanded", "true");
             submenu
                 .show()
                 .removeAttr("aria-hidden")
-                .attr("aria-expanded", "true")
-                .position(position);
+                .attr("aria-expanded", "true");
         },
 
         collapseAll: function (event, all) {

lib/web/mage/menu.js

@@ -685,6 +685,8 @@ define([
         expand: function (event) {
             var newItem = this.active &&
                 this.active
+                    .children('.submenu')
+                    .children('.row')
                     .children('.ui-menu')
                     .children('.ui-menu-item')
                     .first();