No, None of us have the groups in the local address but nor do we have replicas of the Domino Directory. But but both of us have a replica of the condensed address book. So… Same system (databases), same configuration.
There is an option in a person’s mailfile as well - under delivery options there’s a checkbox ‘Do not expand personal groups’. Maybe this is checked for some. (I’m now assuming the group is in the condensed address book - this still won’t work if the group is just in a server address book).