It could be related to how OAuth is handled. However, nobody in this community will be able to help troubleshoot that issue with you because we do not have access to the imageRUNNER machines, the software they use, or how they do what they do (i.e., the setup process to configure OAuth).
Credentials not persisting beyond a power loss or internet outage is kind of a big deal, so if it were a widespread issue, I'd like to think a lot of others would have reached out before now. That makes me wonder if it could be an issue with the configuration. OAuth 2.0 configuration is not easy to implement. - it requires in-depth knowledge about the Microsoft Graph API, Entra, and the details of how security in your organization works (including token expiration).
Having said all that, please know that I am not a tech support person. What I've said above is what I know from my own personal experience using the Microsoft Graph API, and trying and failing numerous times to setup various ways to send/receive mail. It is not easy at all. There is no "app" that interfaces between your printer and Microsoft, it's basically a form so the data you put in gets fed to Microsoft. It's validated, and the machine can then access Microsoft services. What is probably happening is the token is expiring by design - when you setup an access token, you have to give it an expiration date for security purposes. The printer may not be getting kicked out of your Microsoft account when the credential expires because it was already validated as a safe device, but when it comes back on after power or internet outage, it re-validates and Microsoft doesn't recognize the expired token. You'll need to check your token in Entra. That's not something we can help with, it's part of MS365.
