FontAwesome icons do not show

Hello!

I just installed the current version of the codon theme, however the icons over the posts (calendar, user, etc.) do not show, only boxes instead of them. These icons are not images, rather based on the FontAwesome font.

The proper CSS and font files seems to be at their correct location.
What is strange, that on the theme customization panel of the admin section (where one can preview the theme) these icons do show, however not on the actual page.

My site is available here:
https://ikdok.elte.hu/

I created a child theme to make some minor customization (e.g. logo), however this bug was present instantly after the installation of the parent codon theme.

Thanks for any suggestion or help.

Regards,
CMate