I recently updated my site to WordPress 4.9.1 and ACF Pro 5.6.7. I noticed that the “Custom Fields” metabox (from WordPress Core) no longer displays anywhere, nor does it appear in the “Screen Options” of posts, pages, and other post types that support custom fields.
On this site, ACF Pro is NOT controlling metaboxes on Posts or Pages, just the custom post types I defined. I was using core custom fields on my site from before ACF was activated, and I don’t really want to mess with that working functionality right at this moment.
Is there a way to bring it back, other than downgrading the ACF Pro plugin?