I am having a similar but slightly different problem.
I have a wordpress.com account, a www.ads-software.com account, an API key, and multiple blogs.
One of my blogs is https://digitalcorpora.org/. I am trying to get the API key to work with the blog, but I get this error when I try:
WordPress.com Stats needs attention: please enter an API key or
disable the plugin.
The API key “**********” belongs to the WordPress.com account of
“simsong”. If this is not your account, please re-enter your API key.
Add new blog to my account
Do this if this blog is new or has never been associated with your API
key. This blog will be added to your WordPress.com account.
The problem is, when I click “Add new blog to my account,” I get this error:
The owner of that API Key (digitalcorpora) is not on the access list
for this blog (8011489). To be added to the access list, you must
contact support
What should I do?