We're using articles GraphQL Query to fetch articles of the store. Attached is the cURL request and response payload. The API responds with 200 status code with empty articles array as well as true in hasNextPage field and null endCursor
Thanks for your post. When testing on a couple test stores where one had blog articles and one did not the issue described with pageInfo values didn't occur. So if you're able to consistently have it happen on that one store please [request email assistance from Partner Support] using the 'App Development and API' topic to enable a more direct investigation.
This is happening for us too. In our case it is because of a deleted customer account with the same email as an active account. If you include "first:1" in the query, the edges and nodes are empty arrays, hasNextPage is true, but endCursor is null.