Using Product categories to generate menu - not working

I have created a menu for my sites using product categories, unfortunately this does not work.

The navigation menu bar seems to add 'store/' into the url which seems to be where it is going wrong.

I am using the Global Products Categories widget in my side bar which picks up the same product categories and this works perfectly as the link url's omit the 'store/' .


Menu navigation url for 'dressing up' is:
this does not find any products

Sidebar Global product categories url for 'dressing up' is:
this does find products

This affects all product categories as far as i can see.

Can anyone help fix this please? I am sure I could do it by creating custom url's in my menu but would prefer a real fix, as no idea why it is behaving differently whilst using the same product categories/slugs