ACF does not run ‘the_content’ on wysiwyg fields. Add a second filter
function the_shortcode_filter($content) {
$block = join("|",array("columns", "first", "second", "block-bullets", "loan-terms-from"));
$rep = preg_replace("/()?\[($block)(\s[^\]]+)?\](<\/p>|<br \/>)?/","[$2$3]",$content);
$rep = preg_replace("/()?\[\/($block)](<\/p>|<br \/>)?/","[/$2]",$rep);
return $rep;
}
add_filter("the_content", "the_shortcode_filter");
add_filter("acf_the_content", "the_shortcode_filter");