Activity Stream from: Organization Error group not found

Hi, I am running CKAN 2.3a, it seems there is a bug also present in master.ckan.org concerning organization filtering.
After I follow an organization and I try from the dashboard to filter the activity stream to see only the activity stream of that organization, I get an error: 

404 Not Found
The resource could not be found.
group not found

It seems a bug, but in the demo instance http://demo.ckan.org/ everything works fine. 

Could you please check?

Thank you.

- Fabrizio