Developer toolbar has revealed a syntax error which is not being trapped.
"Uncaught SyntaxError: Unexpected number"
It relates to the variable sweetcaptchaPluginVersion.
You have assigned an invalid number. The variable should be in string format I believe for the versioning style you are using. Two decimal points in a number is invalid.
window.sweetcaptchaPluginVersion = 3.1.0;
https://wordpress.org/plugins/sweetcaptcha-revolutionary-free-captcha-service/