Kmenu will only show a sub-menu if there is more then 1 item, this is how it works for all my menu's EXCEPT for the Games menu.

if for example we have:

Games
...Board games
......Mahjongg Solitaire
......Reversi Board Game
...Card Games
......Patience Card Game
...Puzzle
......Minesweeper

you expect to see:

Games
...Board games
......Mahjongg Solitaire
......Reversi Board Game
...Patience Card Game
...Minesweeper

but instead I see:

Games
...Board games
......Mahjongg Solitaire
......Reversi Board Game

now if I add a 2nd item via kmenu editor to the group Card Games and one to the group Puzzle then I get:

Games
...Board games
......Mahjongg Solitaire
......Reversi Board Game
...Card Games
......Patience Card Game
......Fake item 1
...Puzzles
......Minesweeper
......Fake item 2

another way I can make it work is do this add a fake item under Games and then I get:

Games
...Board games
......Mahjongg Solitaire
......Reversi Board Game
...Patience Card Game
...Minesweeper
...Fake Item

now all other menu group work as they should, its just Games that either needs 1 fake item in the group "Games" or 1 fake item in each sub-group which only has 1 item

I suspect something is corrupted somewhere but where exactly are the menu/sub items stored, I for sure can't find them in /home/user/.kde/share