Live Update content revisions are stored differently on the management server than in Symantec Endpoint Protection Manager versions earlier than 12.1.5.
Downloading Live Update Administrator See Configuring clients to download content from an external Live Update server.
If your clients cannot reach any server on the list, then they are still able to update from the Symantec Live Update server.
Symantec Endpoint Protection Manager no longer includes legacy support for Live Update Administrator 1.x.
This increase occurs if the number of revisions you had before the upgrade is less than the new minimum default, based on the above criteria.
See Reverting to an older version of the Symantec Endpoint Protection security updates.