1.For any other user this clients are visible?
Login with the default admin account and see whether you are bale to see this clients..
In the client go to help and support--->troubleshooting and check it belongs to which server and group and check for the client in the same group.
If you are setting a limited administrator have a look in the below doc
How to change Manage Group permissions for Limited Administrators in SEPM for multiple groups
2.Which is the version you are using?Older versions was having some problems related to automatically going to Internet and it is fixed in RU5
Scheduled LiveUpdate still launches LuAll.exe although the "Use a LiveUpdate Server" option is unchecked
Fix ID: 1652473
Symptom: After migration, LiveUpdate still uses LuAll.exe to download content from an internal or external LU server, regardless of whether the Use a LiveUpdate Server option is checked.
Solution: Scheduled LiveUpdate settings are cleared and the Symantec Endpoint Protection client uses the LiveUpdate policy from the Symantec Endpoint Protection Manager.
LiveUpdate tries to contact external LiveUpdate Servers despite policy setting
Fix ID: 1678207
Symptom: The Use a LiveUpdate Server setting is not honored, which causes Symantec Endpoint Protection clients to download content from external LiveUpdate servers.
Solution: The Use a LiveUpdate Server setting is checked before attempting to download content.
3.In the migration wizard you are having the option for downloading the host name and IP address from a text file
Refer this figure