Hi,
on the affected client, collect the communication sylink.log according to:
http://www.symantec.com/docs/TECH102412
I am sorry to say that "Update content" command is a useless feature for troubleshooting purpose, the client executes commands as well as content updates at the next heartbeat without any manual action, if there is a connectivity isssue or anything broken, "update content" does not fix or workaround it. It is much better to execute "update policies" on the client to trigger the communication while recording it with the sylink.log instead of waiting a full heartbeat.