Why aren't my newsletter signups from Shopify showing up in MailChimp?

I’ve recently connected our Mailchimp and Shopify accounts with the purpose of collecting contact information through our newsletter sign-up function. However, I’ve entered several different email addresses to test, and do not see them showing up in MailChimp. I reached out to MailChimp support, and got the following response..

"After running a few test on your Shopify store, I was able to confirm the same issue as you’ve described. Taking a closer look at the signup form I noticed the the Google reCAPTCHA is not functioning properly, which could be causing the signup form to not work correctly. This would explain why those signups are not showing up on the Mailchimp account as well.

Being that this is the built-in Shopify Signup form on the “Debut” theme. We wouldn’t be able to provide an exact detailed reason as to why that is going on but the Shopify team may be of help."

Can anyone advise on the best next step?