[Heli]

Is there any way the admin can see the discussion of hidden group? In case of not wanted discussion the group would be good to be deleted.

[Paul Wong-Gibbs]

Site admins can see/should see all groups, regardless of their privacy setting.

[Heli]

Yes. I can see the group, but not activity streams for example.

[Hugo Ashmore]

@helijussila
Yes activity is not viewable despite super admin access to hidden groups, I had a feeling I’d seen a ticket on this, and just ran across it again:
https://trac.buddypress.org/ticket/2602

So upgrading to 1.2.6 should sort the issue out,