Appologioes, there were two errors in my code. First was the filter name, second was a double closing div
.
Here is the tested working new code which I have added to your functions.php
file.:
function sf_override_date_figure_overlay() {
global $post, $sf_options;
$remove_dates = $sf_options['remove_dates'];
if ($remove_dates) {
return;
}
$post_date_month = get_the_date('M');
$post_date_day = get_the_date('d');
$post_date_year = get_the_date('Y');
return '<div class="date-overlay narrow-date-block"><span class="month">'.$post_date_month.'</span><span class="day">'.$post_date_day.'<span class="month">'.$post_date_year.'</span></div>';
}
add_filter( 'sf_before_recent_post_thumb', 'sf_override_date_figure_overlay', 30 );