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.
I was testing this with simple batch scripts, to show up events, the script should update the system. It's a normal bahaviour.
sorry my reply was actually related to your other question (How to create rule for a script can change a whitelisted file? )
As for obserervation events not always getting send towards the ePo server. we experience the same issue and is currently under investigation.