In Automic Automation version 21.0.8, using the Service Manager Dialog to shutdown the system:
Nothing happens and the system will not shutdown.
If you attempt to stop a single process via the Service Manager:
This works as expected.
Automic Automation version 21.0.8 (including all hotfixes for 21.0.8).
This was due to a defect in the Shutdown System option in version 21.0.8.
This has been resolved in version 21.0.9, published as of Dec 18, 2023.
The workaround is to use the Service Manager for version 21.0.7 until you can upgrade.