Yes. My sister told me (she’s not a member of the private group).. so I signed in as her and I saw the posts myself. You can’t see the group from her side.. but you can see the posts in the feed on her profile even though she’s not a member of the group.
No. I installed the same theme and plugins on another domain and it works there… I already manually reinstalled buddypress and bbpress. And I pressed the reinstall wordpress button on the dashboard updates…. This is beyond my knowledge.