Posts don't show without purge page cache

This wasn’t happening with previous versions of WP, and since I hadn’t posted for a while, I hadn’t noticed a problem. But after posting for a few days, I noticed that though my posts were live and accessible, my blog page (listing several posts) wasn’t updating. Not until I manually purged that page’s cache. Apparently that happened automatically, but not now?

At any rate, I found a solution in the following link, coded, uploaded, and now my blog page updates after I do a new post (or update — that wasn’t working either).

https://www.michaelbrentecklund.com/wordpress-php-wp-save-post-w3tc-clear-all-caches/05-16-2012/

I’m still scratching my head at what changed under the hood to make me have to do this.