alcero
Upgrade to v1.17.3, install the latest build of the OAuth2 plugin, get a new token, and you should be good.
The Access Token will always expire in 1 hour by default. We then use the Refresh Token to refresh the Access Token on expiration which will give a new Access Token, new Refresh Token, and new expiration time. There was however a previous bug where we weren't updating the Refresh Token so about 90 days later it will stop working and you have to manually get a new token. With v1.17.3 and new build of OAuth2 plugin the bug was addressed. Once you do the above, moving forward, the tokens should only stop working when the Client Secret expires OR something from MS end invalidates the tokens (usually very rare).
Cheers.