Hi @ribaron,
i had the same problem. And i've solved the problem with the following code. Replace the code:
{if $captcha eq "recaptcha"}
{$recaptchahtml}
{else}
with the following code snippet:
{if $captcha eq "recaptcha"}
<script src="https://www.google.com/recaptcha/api.js" async defer></script>
<div id="google-recaptcha" class="g-recaptcha center-block" data-sitekey="{$reCaptchaPublicKey}"></div>
{else}
That works for me.
Best,
Giuliano