Ocsagent 2.4.2 shows no OS version in Ubuntu 18.04

Ocsagent 2.4.2 shows only Ubuntu (no version) in Ubuntu 18.04. The ocs agent was Installed from sources.

lsb_release -a shows:

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.1 LTS
Release:        18.04
Codename:       bionic