I’m experiencing the same issue. The “ReCaptcha Version” is set to “reCaptcha Version 2”; but nevertheless, the API request URL still includes “ver=3.0” and render=<site key>. The request to https://www.google.com/recaptcha/api.js is returning a 400 response, presumably because it’s including render=<site key> rather than render=explicit.
I have Contact Form 7 v5.1.8 and Recaptcha v2 for Contact Form 7 v1.2.6.
