Custom password set/reset link in same URL format as default does't work

Question

I'm trying to add custom wording to the basic WordPress registration password set/reset email. I'm using the plugin New User Approve to approve all users, but that doesn't seem to impact my issue. The problem is that the password set/rest link I'm emailing is identical to the default Wordpress link - except of course for the keys - but it doesn't work.

The default WordPress emailed link looks like this:

https://example.com/wp-login.php?action=rp&key=gicOc3FFIcDzf5WZvKBV&login=username

My emailed link looks like this:

https://example.com/wp-login.php?action=rp&key=V9gnJAe359tkn2dPOMXo&login=username

The default link works; my link throws the message "Your password reset link appears to be invalid. Please request a new link below."

How can I get my custom email to link to the password setting page https://example.com/wp-login.php?action=rp and not https://example.com/wp-login.php?action=lostpassword&error=invalidkey

Is the key not valid? Expired? Not output correctly? Using rawurlencode($user_login); from Check Password Reset Key Not Woking does not help.

To generate the custom email, I'm using

  function my_custom_message( $message, $user ) {

            $user_login = stripslashes($user->user_login);
            $key = get_password_reset_key( $user_data );

       $rp_link =  wp_login_url() ."?action=rp&key=$key&login=" . rawurlencode($user_login); 
    return $rp_link;
}

        return $rp_link;
    }
    // add a new custom approval message
    add_filter( 'new_user_approve_approve_user_message', 'my_custom_message', 10, 2 );

Answer 1

The error (flagged in debug) was that I was using $user_data in the line

$key = get_password_reset_key( $user_data );

instead of $user.

Works now on WP 4.9.6.