Captcha Spinning Arrow

Have a Contact 7 Form with a simple Captcha.

http://pbpromos.com/testpage/

http://pbpromos.com/testpage/

When you fill in the fields and submit the form after putting in the Captcha letters, you get a spinning arrow that never stops. ( This happens even if you do not fill any fields. )

Any ideas of how to get around this problem?

https://ww.wp.xz.cn/plugins/really-simple-captcha/