I think the JS alert was caused by my ad blockers. When I turned off both uBlock Origin and Firefox’s built-in one, the request was sent to Mailchimp successfully. Have not received a confirmation though which might be related to the issue you mention.
This seems to be an issue on mailchimp’s end, not ours – their servers have been having outages all morning. I recommend trying again in a bit.
I think the JS alert was caused by my ad blockers. When I turned off both uBlock Origin and Firefox’s built-in one, the request was sent to Mailchimp successfully. Have not received a confirmation though which might be related to the issue you mention.