How can the LiveUpdate button be enabled on a SEP client as the client user interface has the LiveUpdate button grayed out

OR

How to enable "Allow the user to manually launch LiveUpdate" checkbox, as it is found to be grayed out in the LiveUpdate Settings Policy's Advanced Settings?

Symptoms
Only content updates are received from the Symantec Endpoint Protection Manager (SEPM) console, users of SEP clients are unable to run LiveUpdate themselves. From the SEP user interface, you'll find that the LiveUpdate button is grayed out and unavailable.

The default policies applied to an installation of SEPM and SEP will cause the LiveUpdate button to be unavailable for SEP clients

Make the following change to the LiveUpdate policy:

Policies > LiveUpdate > LiveUpdate Settings policy > Edit the policy

By default, "Use the default management server (recommended)" is checked.
You will find under the Advanced Settings, "Allow the user to manually launch LiveUpdate", is grayed out.
To enable this checkbox, go back to Server Settings: Check the box for "Use a LiveUpdate server", leaving the following checked:
"Use the default Symantec LiveUpdate server", as this setting will enable users to run LiveUpdate manually via the Internet.

"Use a specified internal LiveUpdate server" would only need to be chosen if you wish your users to manually download updates via the LiveUpdate button from your own LiveUpdate server, rather than from Symantec LiveUpdate servers.

Save and apply the policy to the relevant groups. The LiveUpdate button will now be active on SEP clients. Hence, users are now able to run LiveUpdate manually.