The issue was found and fixed with:
Automation.Engine 12.3.0 - pending release
Automation.Engine 12.2.3 - pending release
Automation.Engine 12.1.5 - released 2019-05-20
Hotfix-Description: AWI search does not find objects in new clients after client copy.
A problem has been fixed where objects of copied clients were not found by the AWI search.
Now, when a client copy has been detected, the entire client gets indexed to the index search.