I've accessed your website and it seems there's no issues with your post featured images, this leads me to think you might have solved it or it was just a caching issue as you've mentioned.
Forcing All Pages to HTTPS
For ensuring everything else is loaded over
https, make sure you change the site and home urls under Settings >> General in WordPress Admin. Make it read https://meta-game.org - and then Save changes.
Additionally, If you’re looking for a simple way to secure WordPress logins (the wp-login.php script) or the entire wp-admin area, you could set one the constant bellow in
Inspecting the mixed content sources
Regarding the mixed content being loaded from both the
https protocols, I'd suggest you to inspect your theme's templates or even a plugin and search for anything hard-coded with
http and then fix it.
When developers are aware of this, it shouldn't be a problem, but some times a few themes come with the
httpprotocol hard-coded within its templates, that's a bad practice I know, but we've got to fix it somehow.
A pretty simple method for inspecting is to load the page via HTTPS, and then right-click anywhere on the page and click “View Page Source”, “View Source”, or “Source”, depending on your browser.
Then use the “Find” command, Edit -> Find or
(Ctrl+F or Cmd+F) and search for:
Long story short, you’re manually looking for images, scripts, iframes, and all other assets served via HTTP instead of HTTPS.
Make note of each item sourced via HTTP and you’ll get an idea where to find the problem.
Thoughts on fixing the mixed content
Using Relative URLs
This is the simplest fix. If an asset (image, script, etc.) is hard-coded into a plugin or theme, change it from
Typically, this is most useful when including assets from other servers, like Google scripts, API scripts, or iframes.
Before doing this, however, you need to make sure the HTTPS version is available. If loading an asset from a site that doesn’t have HTTPS enabled, it’s probably best to remove the reference entirely (i.e. comment out or delete) or to save the asset to your own server and change the source to load via your site instead.
Using Proper WordPress Coding Standards
A nice approach is to use the WP function
is_ssl() to conditionally load assets in templates depending of the protocol that is being used by the website, e.g:
$protocol = is_ssl() ? 'https:' : 'http:';
Enqueueing an external content with the above method:
Instead of manually setting the protocol...
wp_enqueue_script('bootstrapjs', 'https://cdn.jsdelivr.net/bootstrap/4.0.0-alpha.5/js/bootstrap.min.js', 'false', null, TRUE);
Let's do it dynamically
wp_enqueue_script('bootstrapjs', $protocol.'//cdn.jsdelivr.net/bootstrap/4.0.0-alpha.5/js/bootstrap.min.js', 'false', null, TRUE);
Assuring your website does not serve mixed content, provides your visitors with a pleasant browsing experience, the described methods here should help you to keep your site on track while using ssl.