Hi,
Please try to run "Update-CsAddressBook" as Admin in SFB Control panel, this will force the update for the address book update of SFB.
Then, please sign out the SFB client, and try to clear the sip cache files, then reconnect SFB to see if the legacy distribution group is still there.
To clear the cache file, please follow the below steps:
1.Sign out Skype for Business -> delete
sign-in information
2.Delete sip folder under: %UserProfile%\AppData\Local\Microsoft\Office\16.0\Lync.
3. Reconnect and see if the issue is fixed in your contact
Note: You might see two subfolders under "Office" which are "15.0" and "16.0".
For locating the specific cache files actually where they are, it depends on the exact edition that you installed, you could check it by clicking "Help", then navigate to "About Skype
for Business" in the client to see the version.
If the above cannot get it works, please try to force the AD replication just to start from the source of the distribution group creation. See this thread to see if it helps: https://social.technet.microsoft.com/Forums/exchange/en-US/6a0577dc-acc1-4010-b4d7-37de16aafcbc/unable-to-delete-legacy-distribution-group?forum=exchange2010
By the way, MS has never provided any GPO method for forcing the publish or update the distribution group from Admin side for users.
Kind regards,
Calvin Liu
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