pre cache not working since update

No, it’s still working for me and for others as well.

Please look into logs & error messages, otherwise I cannot help.

UpTimeRobot.com

Pre-cache I belief works with Wp-Cron, which is triggered by traffic/site visits. No traffic, no Cron.

Signup for a Free account to get http traffic. Or Google Cpanel WordPress Cron Job..

As a side note with regards to wp-cron requiring traffic, you can also set it up as a regular cron job (I’ve done some myself) which takes out the traffic requirement. See https://support.hostgator.com/articles/specialized-help/technical/wordpress/how-to-replace-wordpress-cron-with-a-real-cron-job