Hello @murphy2347,
We apologize in advance for this inconvenience. We validate every Mailchimp API Key stored according to the documentation listed in Mailchimp.
https://mailchimp.com/developer/marketing/api/root/list-api-root-resources/
To ensure your API Key is valid, can you try copying and pasting the code below into your terminal? You can replace YOUR_MC_API_KEY
with your API Key (xxx-usx
) and YOUR_MC_SERVER_PREFIX
with your Mailchimp server prefix (usx
).
curl \
--header "Authorization: Basic YOUR_MC_API_KEY" \
"https://YOUR_MC_SERVER_PREFIX.api.mailchimp.com/3.0/?fields=account_id"
If your API Key is valid, you will get your account id data, otherwise, you will get an error message which will explain why your API Key is not valid. As an example, you can see the screenshot below.

If you have validated your API Key in the above way and it is valid, there may be something on your site that we need to investigate further. However, we will wait for further news from you.
Thank You