Hi,
Thank you for reaching out us.
You are facing this issue because we have added the nonces while submitting the forms in the plugin. Nonces help to protect URLs and forms from certain types of misuse, malicious use. These nonces have a limited life span and when these get expire issue of invalid request arises. To solve this refresh the page or clear the cache of the browser, it will generate nonce again and removes invalid request issue.
If you have any further questions please reach out to us at info@xecurify.com
Thanks,