Can't Submit Form When reCaptcha is Present

I have created a custom form and it works fine normally. I decided to add reCaptcha to the form and this also appears to work in terms of me clicking the box and getting the green tick. When i try to submit the form i get an orange box. This is meant to mean spam. Why is this happening? If i use the exact same input values in the form it submits fine, but whenever reCaptcha is used it fails.

Since the green tick is showing up in the box i would have assumed that this meant it had confirmed that i was not a robot. Why is it still failing for spam?

https://wordpress.org/plugins/contact-form-7/