The backend may be unchecked.

I believe you are reporting this on the wrong plugin. Many captcha plugins have very similar names.

This plugin performs full back-end checking against the Google Captcha API v2. Even with the javascript disabled or front-end modifications to the DOM, the captcha will not let you through.

The old captcha console for creating keys was very straightforward. Google recently moved this under Cloud Console as part of sweeping moves to consolidate, so this dashboard view is fairly new and much less clear.

The checklist wizard on the cloud console is walking you through a variety of steps with names like frontend and backend for a variety of v2 and v3 captcha offerings. In reality, these are not related to the frontend / backend functionality of the plugin, which uses checkbox v2 and does not require scores.

If you have created and input a public and secret key to the plugin configuration page, you are fully set up and the plugin is checking responses with Google as expected. The keys in Cloud Console are fully backwards compatible with the old captcha console, and with the plugin’s approach to integration.