Hey, I have exact same problem, except when I set parent_cat to -1 on line 449 of the code:
groups_update_groupmeta($bp->groups->current_group->id,'parent_cat', 0);
to
groups_update_groupmeta($bp->groups->current_group->id,'parent_cat', -1);
Nothing happens. Did I get it wrong; is there another place?
Thanks,
Nick