Can’t submit CF7

When ChimpMatic lite is activated and connected to CF7, all submissions for CF7 fail with 500 errors.

In the backend, on the ChimpMatic settings- the debug log button doesn’t work. Crashes the whole backend repeatedly.

I have tried redownloading the plugin, but no success there. I think these problems may have come about with the latest version, though not sure on that.

Mailchimp appears connected, all settings are correct per documentation. What should I try next?