ah, sorry, I missed that you'd linked to your github repo.
Hmmm. An easy thing to troubleshoot would be to just put console.log statements throughout your plugin. That is what I would do first, as that would narrow down the area that is causing the issue.
The oauth2 endpoints look good here: https://github.com/rgigante/nodebb-plugin-sso-oauth/blob/master/library.js
But the profile information looks a bit suspect. From git blame it looks like you didn't change that.
This page documents the profile data you'll get back, so I think you need to update the profile information extraction section.
Here's how the fusionauth plugin does this: https://github.com/FusionAuth/nodebb-plugin-fusionauth-oidc/blob/master/library.js#L91