How to add menus from CLSID to folder background context menu?

I've disabled the standard Windows context menus and created some custom ones pulling in various Windows ones by following this:

However, adding specific Windows context menus to the folder background context menu doesn't appear to work - it just doesn't appear:



The exact same 'Function' line works fine in the menus configured through "File types":



Am I doing something wrong?

Sorry for bumping, but anyone have any ideas here?

It may not be possible right now, but I need to look in more detail.

Many thanks, appreciate your attention