Shopify recently added an extra layer of Captcha protection which has caused the Newsletter signup forms in our themes to stop working.
While Shopify is working to resolve this on their end so that older Newsletter forms can work with the new protection, in the meantime, we have updated our themes to accommodate the new protection and resolve the issue with the form. The Newsletter signup forms are working as expected in the latest versions of our themes. Learn how to update your theme
However, if you aren't able to update your theme currently, you can disable this extra protection by following these steps.
With this feature disabled the Newsletter signups in older theme versions will be added to the Customers List as expected.
The standard Captcha protection will still be in place, this would only disable the new layer recently added by Shopify.