Hi, Julien.
In Passport's settings in web UI, please change logging level to "debug" and restart "passport" service.
After that, retry the failing flow while recording network trace with browser's dev console, and export it as HAR file. You can use steps listed [here](https://www.inflectra.com/support/knowledgebase/kb254.aspx) - please use Firefox for that task, Chrome's HARs are flawed. Also don't forget to set "Persist log" and "Disable cache" checkboxes in the console to save everything, not just the recently loaded page.
Share the HAR file with us, and also next logs:
- `/opt/gluu/node/passport/server/logs/passport.log`
- `/opt/gluu/jetty/oxauth/logs/oxauth.log`
- `/opt/gluu/jetty/oxauth/logs/oxauth_script.log`