@buro86 We suggest to disable all extra plugins because if you did update, this couldn't be related with the theme itself. And as you can see on http://pasteboard.co/vLq94JJTr.png everything is fine with your menu in Safari.
Thank you muffingroup, if it can help anyone, this error is caused by the WP Rocket plugin. Unhecking the CSS & JS Minification & Concatenation options & clearing the WP Rocket cache made the menu appear again, even in older Safari versions.
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please update your theme to it's latest version and all will be fine.