Menu disapeared after updating the Theme

I was just informed by 2 visitors of my website www.przemianaumyslu.pl that they cannot see the main menu since yesterday. It happened the same day I updated the Catch Box Free Theme that I am using. I can still see the menu on my computer but for some reason some people cannot see it on different computers. Can you please tell me what is the cause of it and what I can do to fix that? Best regards, Rafal