Answer by Michael for Link won't show using the_permalink();

because the_title() expects a string for the $before and $after args, you need to use the string version of the permalink, in a string concatenation;

<?php the_title('<h2 class="wow"><a href="'.get_permalink().'">', '</a></h2>'); ?>

you also had a missing >.

https://developer.wordpress.org/reference/functions/get_permalink/