Your doing well as of now.
We are doing an integration between microsoft 365 by using oauth. Configured oauth_config.json file based on our documentation.
After the integration we can able to see the access_token and resfresh_token as well, generally the access_token expired after sometime, at time platform do automatically get a new token from thridparty application using the resfresh_token, but it does not work.
Let me know if you know anything about to fix that issue.