‘Not Secure’ even with valid certificate

It is still labelled as “Not secure”

FF tells me that’s because of images.

You have mixed content at your site.

Change all http to https.

Install the plugin Better Search And Replace. Search for https://example.com and replace with https://example.com ;

Review this tutorial: https://www.wpbeginner.com/plugins/how-to-fix-the-mixed-content-error-in-wordpress-step-by-step/

Thank you for the response! I have used this and an HTTPS Checker to change the URLs. It has slightly improved. Now the website is “not fully secure”, and I still cannot manage to solve this issue.

I see the FULL LOCK. No more “not fully secure” message.

Clear all your cache.