Menu problem

Hey,

I have a problem with adding new categories, pages or posts to my menu at https://www.thailandliving.se
As you can see the Destinations have many submenus and I can′t add more – they don′t get saved.
Is there a limit?

When I try to add a new page to the meny it wont′get saved and after I click on Save the Assigned Menu settings goes back to Select a Menu.

What can be wrong?

Thanks
Charlotte