Same issue here.
API works fine, green lights where required – plugin live on the site.
Some users are successfully added to Mailchimp list, but 95% of the time, I experience ‘X – Failed to add user – 400’
I’m not in a position to change Themes as I don’t want to risk any deeper issues, as I have customised the Theme’s CSS in places. I would prefer this problem to be fixed on your plugin, as a few users are clearly experiencing this issue.
Please let me know what a remedy might be, or if anyone can recommend a better plugin, I’d happily look at others.
The theme I’m using is ‘Eventim’ the URL is https://london.fastforward.xyz and you’ll find the form at the bottom of each page. try it, and see if it works for you.
Simon
