Header Secondary Menu – UNABLE TO ACCESS SUB MENUS!

I have sub menus which are now inaccessible on hover https://www.samuiluxuryboat.com See menu for “CHARTERS” you can only access the 1st sub menu item! Hover over 'joining trips' menu and you will find you cannot access 'catamaran joining trips' PLEASE ADVISE A FIX. I have updated the theme to version 4.4 already. Thank you Chris