Hi,
There seems to be a configuration issue somewhere on your website, as the WordPress core returns an incorrect ajax handler URL: https://i.imgur.com/FjWX9bo.png
The plugin tries to make a request, but the ajax handler URL wordpress gives to it is on a different domain. If you recently moved the site, or changed the site URL, then make sure to check all the related site URL configurations. Somewhere it is not set correctly, it refers to that other domain.
