You can monitor network activity with a built-in tool in Symantec Endpoint Protection (SEP).The tool that can be accessed via the SEP interface in Status > Network and Host Exploit Mitigation > Options > View Network Activity.
This shows an overview of the network activity on the endpoint system.
When you switch the View to Connection Details, the list of Running Applications populates and then disappears returning to Large Icons view.
This issue is fixed in Symantec Endpoint Protection 14.2 RU2. For information on how to obtain the latest build of Symantec Endpoint Protection, see Download the latest version of Symantec software here.