Broadcast Roles were implemented in our last release (Viking). This allowed the role for broadcasting to be assigned to members of the community, by default we allowed all members to broadcast to everyone in their site.
At the request of many clients however, we have adjusted the default roles in the current release (Wolf). Previously all members could broadcast to all the groups in a community by default. Now they cannot. This setting was only changed in communities where it was currently set to the default and had never been changed previously.
Re-enabling that setting can be done in your Igloo control panel. Select Manage Groups, manage roles and then broadcast roles. Where All Members, or a particular group can be empowered to broadcast to all the groups in the community. More information on the broadcast role can be found on our support site here: https://support.igloosoftware.com/documentation/communityandmembermanagement/users_and_groups