Fixes to fix it :

• Clear Cache – Your browser or WordPress might be holding onto old data. Clear your browser’s cache and, if you’re using a caching plugin (like WP Rocket or W3 Total Cache), clear that too.

• Check Your Plugins – Turn off all plugins and see if the problem goes away. If it does, turn them back on one by one to find the troublemaker.

• Try a Default Theme – Switch to a basic WordPress theme (like Twenty Twenty-Four) to see if your theme is causing the issue.

• Fix a WordPress Setting – Open your wp-config.php file and add this line:

   

  define(‘CONCATENATE_SCRIPTS’, false);

   

  Save the file and refresh the editor.

• Reinstall the Editor Files – The editor (TinyMCE) might be broken. Download a fresh copy of WordPress from wordpress.org, then replace the /wp-includes/js/tinymce/ folder using FTP.

• Check File Permissions – Make sure WordPress has the right access:

  • Set files to 644 permissions.
  • Set folders to 755 permissions.

• Look for Errors in the Console – Open your browser’s developer console (press F12, then go to the Console tab) and check for errors. If you see any, they might point to a plugin or theme issue.

• Update Everything – Make sure WordPress, your theme, and all plugins are up to date. Updates often fix bugs like this.