If you add reCAPTCHA to your comments form and it doesn't show up but when you're trying to submit the comment you see the error message, then the following information can be useful.
First of all, check the browser console for errors. All errors should be fixed as they can cause the problems with reCAPTCHA work.
Our plugin uses the following hooks to display reCAPTCHA: 'comment_form_after_fields' and 'comment_form_logged_in_after' that are present in the standard WordPress 'comment_form()' function.
If your theme doesn't use that function to display the comment form, you should complete the following steps:
1. Open the file with the form (where you would like to add reCAPTCHA);
2. Find a place to insert the code for the reCAPTCHA output;
3. Then you should add:
<?php echo apply_filters( 'gglcptch_display_recaptcha', '', 'comments_form' ); ?>
If you have any additional questions, submit a private request here - https://support.bestwebsoft.com/hc/en-us/requests/new.