Menu with sub-menus opening off screen

I recently upgraded spacious on this clients website and the menus have “disappeared” according to the client.

On investigation, I see that they haven’t disappeared – they are just expanding out beyond the screen view making it impossible to see
(Try “Novels & Short & Reads” -> “Novels” -> “The Buzz” -> “Menu not showing”

I’m assuming there was a change to how the menus expanded in recent versions and was wondering how I get the menu to show how it used to (opens to the left)

The page I need help with: [log in to see the link]