jadijadi

Fixed it. First I checked the problematic posts ID in wp_postmeta table:

SELECT * FROM wp_postmeta WHERE post_id = 13901;

There were 50+ _encloseme fields. This means one _encloseme is created each time I saved the post but the wp-cron is not processing them. After some troubleshooting, adding this linke to wp-config.php fixed the problem by starting the wp-cron.php on each site visit:

define('DISABLE_WP_CRON', false);