I don't recall it not working. Though I don't use menus very often as I prefer making them manually.
Though if you say it's broken, it's worth fixing instead of just saying it's broken.
I didn't say it's broken, I just asked if I was wrong in thinking it doesn't work properly with sub menus, and if i should be doing something differently. Happy to try and fix it once I know it's broken and it's not just me using it incorrectly.