Why Don't All Users Show Up When Adding Them Under Groups?
Users won't show up as suggestions in the mapping config page until they have logged in at least once, but you can still just type in the username:

More in On-Premise
How to Deploy CodeScene On-prem?How to Enable OKTA Single Sign-on (SSO)?How Can I Ensure Smooth Performance of the CodeScene Server?What Are CodeScene’s Deployment and System Requirements?Still need help? Ask the team