OAuth2 with Azure/Microsoft 365 loops back to the home screen after authenticating. No error shown.

Delete the plugin instance and create a new one. Only configure client ID, client secret, and the two endpoints (Authorization and Token) -- do not modify the default Scopes. After configuring, make sure the email address/username returned by the IdP exactly matches the Agent's profile in osTicket. If the IdP data does not match an existing agent account, the system redirects to the client portal. Upgrade to v1.18.3 and install the latest OAuth2 plugin build, then restart the webserver and PHP-FPM and clear all browser cache/cookies/sessions before retesting.