How do I fix wp-admin error when exporting reusable blocks?

I am having trouble with the export to json feature of the reusable blocks shown below.

I am getting the following console errors after pressing the export to json link:

1. Access to fetch at 'https://public-api.wordpress.com/wp/v2/types/wp_block?_locale=user' from origin 'https://mytestsiteXXXXX.wordpress.com' has been blocked by CORS policy: Request header field x-wp-nonce is not allowed by Access-Control-Allow-Headers in preflight response.
2. GET https://public-api.wordpress.com/wp/v2/types/wp_block?_locale=user net::ERR_FAILED
3. Uncaught (in promise) {code: 'fetch_error', message: 'You are probably offline.'}

It has been a while since I have used WP.com, so I am relearning some things and just wondering if I have done something wrong or forgotton a really basic step. I am using a test site free site provided by wp.com, I have looked for answers but I have not found anything useful yet.