The SQL table ca_class_def is incomplete and does not contain rows for Windows Server 2019 Operating System.
Following SQL query should return some rows for Windows Server 2019 :
select * from ca_class_def where class_name like '%2019%'
Release : 1403
Component : Client Automation
Make sure that job "Default Software Contents Download Job" linked to SystemEngine has been executed successfully
Otherwise check the CIC logs for error under C:\Program Files (x86)\CA\SC\CIC\logs\CIC.log
Once CIC problem is resolved, recycle caf on Windows Server 2019 machines :
caf register all