On a site hosted on WPEngine, I have all options for caching turned on. Recently, site editors/managers have been making updates to the site that are not consistently rendered on the front end. (On some browsers the updated content shows, on some, the prior content shows). The "Clear all caches" button in the WPEngine settings tab in the CMS resolves this issue… until the next time it comes up again.
The content we've experienced this with is specifically via Advanced Custom Fields options fields (which are used to display site-wide header/promotional messaging). I don't know if that's the only content with this issue — it's just the content that's most frequently updated, so the one that's been observed as such.
WPEngine allows enabling: Page Cache, Object Cache, Network Cache, "Smarter Cache" (which allows "posts and pages to be cached for longer if they haven't been modified in a while"), and Last-Modified headers.
I'm trying to figure out where I need to cache less aggressively so this stops happening. I figure it could be an Page cache issue (as individual page content isn't updated, but rather just printed to the header.php file via the
get_field() function), but then I assume content would be consistently update (or not) across all browsers. So I'm leaning toward it being a Last-Modified headers issue, as it appears to be affecting how the browser loads the page.
Does this sound like the correct evaluation? Are there any sure-fire ways to go about diagnosing and confirming this other than trial/error?