macOS: Accessibility: MenuItems are not accessible

When using VoiceOver on macos the user cannot access menu items. The expected key combination is VO-Shift-DownArrow, but that interacts with the Button, which is used to open the menu. Also trying to navigate the menu with VO-arrows focuses the whole menu popup - not single item. (By default VO key is Ctrl-Option.)

The attached example can be used to reproduce the problem. Press VO-space to open the menu and then try to access it with above mentioned ways.