"Hashcash spam protection only works on single posts or pages"

We would like to use this with our Contact Form 7.

Yet, when we install it and use it in our form (which shows at the sidebar of a Category page…we don’t have single pages in this section, it’s a Q&A thing, where a page per question would be overkill).

Sadly it does NOT work, and just croaks with this message:

Hashcash spam protection only works on single posts or pages

Any ideas what to do to make this work?

Thanks!

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