Hello, thanks for the quick reply!
I have no info about the theme being modified in any way, but here you go:
https://1drv.ms/u/s!ApeUT6WBlBSBgYx_dcRrwNPdHIf1Bg
I figured it doesn’t add the code from header.php, but I know too little about this to get where could the problem be…
Thanks in advance.