What other plugins and theme do you use on the site?
Hi,
These are the other plugins:
Akeeba Backup CORE for WordPress
Akismet Anti-spam: Spam Protection
Big File Uploads
Contact Form 7
Contact Form CFDB7
EWWW Image Optimizer
Gutentor - Gutenberg Blocks - Page Builder for Gutenberg Editor
JetGridBuilder
Media Cleaner
PostX
Safe SVG
Secure Custom Fields
Site Kit by Google
Smart Custom 404 Error Page
SMTP2GO - Email Made Easy
Tabbed Contents Block
Watchful
Wordfence Security
WP Contact Form Mailchimp
WP Fastest Cache
WP File Manager
WP Migrate
Yoast Duplicate Post
Yoast SEO
As I can see it, the issue is caused by a CSS specification in your custom theme. There is this specification for all input fields:
input {
-webkit-appearance: none;
-moz-appearance: none;
appearance: none;
}
If you leave this out, the checkbox will be smaller, but you will be able to see that it is checked. You will have to find a different solution for the design of this.