GD recaptcha issue – unable to login

Hi- i am having this issue with the recaptcha very often – not alwyas but i see it several times a day . My site has very low traffic currently

When i try to login or register, after check ing the captcha images it shows ” Sending info, please wait” and then just keeps showing that (mostly even befre the login button is clicked) and then it keeps that way for 3-5 mins and then shows Authentication expired please try again (pls see image)

This stays for a long time even for many hours- then it clears sometimes only for a few minutes and am able to login.

Sometimes it clears up after i clear the cache (i am using WP -Rocket) but sometimes it does not

Please suggest how to fix this

thanks,
Vivek