I've got the same problem with OG 7.2, but I solved it without views-field-view.
Instead I used OGs own way:
I first made the relationship OG membership: OG membership from Node
to get the OG-Membership of the Group-Content I want to show and then...
...I need the Node of the Group of the OG-Membership and that means I need to make the relationship OG membership: Group Node from OG membership using the first relationship.
So now I have 2 relationships :
- OG membership: OG membership from Node
- (OG membership from node) OG membership: Group Node from OG membership
And now I was able to get access to the fields of the related group by using the relation Group Node from OG membership