An important difference on our servers.
HOW WORDPRESS NORMALLY SCHEDULES WORK
By default it triggers scheduled tasks when someone visits the site, by making an HTTP request to wp-cron.php.
WHY THAT IS A PROBLEM
It is unreliable on a quiet site, since nothing runs until someone visits.
It is expensive on a busy site, since it fires constantly.
And it has been abused to generate load.
WHAT WE DO
HTTP requests to wp-cron.php are blocked server-wide across our fleet.
WHAT THAT MEANS FOR YOU
WordPress scheduled tasks will not run unless you set up a real cron job.
WHAT STOPS WORKING WITHOUT IT
Scheduled posts never publish Automatic updates do not run Backup plugins do not run WooCommerce scheduled actions do not process Email queues do not send Plugin maintenance tasks do not run
WHAT TO DO
Disable the HTTP method in wp-config.php, then add a real cron job in cPanel.
The next articles cover exactly how.