A reply to a mail sent with a distribution list shows the names on the distribution list in the FROM column of the email listings. It should show the name of the person replying. Don.t see a fix in settings.
If you are using conversations, the names of all those who have replied to the thread will be listed there.
Disable conversations using Menu > View > Conversations > Disable Conversations and see if it is any different.
The change seems to have worked. I will continue to monitor and let you know if it did not. Thank you for your help.