subcategories dropping off in the appearance menu

hey there,

I’m trying to organise all my product categories in the appearance menu in the admin section for the main menu. However when I add the final 3 categories and click ‘save menu’ they simply disappear and they do not appear on the front end.

I have a large number of product categories 79 sub, 11 parent to be exact, is there a limit as to how many categories you can feature on a wordpress site?