Since you app has been running on the production environment, this type of problem should be addressed urgently by sending a support request to
email@example.com where our dedicated support engineers can help you more timely.
But be prepared for more information if you have such as a log file with other error code/details, your app type and authentication method (3-legged or password flow) etc.
How is the issue going? You said "We received a status of "blacklisted" on a RingCentral token. The reason given was "I/O operation is failed."
How did you receive that status? Is it the response of some API call? If so, could you please tell me what is the API call? Or you can show me some code snippets. I've never heard of this issue before. Thanks.