I have Solidcore 188.8.131.521 deployed from ePO 5.3 on Windows. When I put the client in Enable mode I can see the events under Threat Event Log but in Observe mode I cannot see any events under policy discovery or anywhere.
What version of windows are you using? we had a similar case with McAfee support and apparently the "script as updater" is not available on all windows versions.
As quoted from the appcontrol 8 product guide and our support ticket:
This feature is not applicable for the Windows 8, Windows Embedded 8, Windows 8.1, Windows Embedded 8.1, Windows 10, Windows Embedded 10, Windows Server 2012, and Windows Server 2012 R2 platforms and Application Control 8.