Having difficulty with activating Pipeline in Next Generation DevOps Center

I migrated from Managed Package DevOps Center to Next Generation Dev Ops Center. Now I am not able to activate pipeline or re-authenticate the Source Control Repository. The branch associated with UAT and Prod seems to be OK, because when I click on the branch it opens OK in GitHub. I am having difficulty is selecting a branch for Integration stage.  

Have anyone got any tips for me to follow, thank you so much.