get_the_post_thumbnail() title and alt attributes not displaying

Turns out this was caused by the following custom theme filter in functions.php. Commenting out fixed the problem. function image_alt_tags($content) { global $post; preg_match_all(‘/<img (.*?)\/>/’, $content, $images); if (!is_null($images)) { foreach($images[1] as $index => $value) { if (!preg_match(‘/alt=/’, $value)) { $new_img = str_replace(‘<img’, ‘<img alt=”‘ . get_the_title() . ‘”‘, $images[0][$index]); $content = str_replace($images[0][$index], $new_img, $content); … Read more