Hi there,
I’ve had the same problem.
I copied the “add_filter(‘body_class‘, ‘vantage_body_class‘);” text from a website to the funtion.php of my template an nothing happened.
My solution:
I changed the “curved” aphostrophs in the code to straight ones.
I think it’s a problem of the character options (UTF-8 or something)
Position for the code:
I found another add_filter so I put the new code above.
Good luck