Missing close icon for the mobile menu

Hi! I’m using the Hello Theme Plus with Hello Theme. On the mobile version, there’s an issue with expanding and collapsing the hamburger menu – it expands correctly, but once it’s open, the “X” (close) icon doesn’t appear. It’s also not possible to replace it in the header options (at least I can’t find any setting for that).

Tested on Iphone Safari and Chrome.

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