This issue is that the security policy on a target Windows Server 2019 has some restrictions, which do not allow a remote scheduled tasks initiated by a DS-Client server.
Please refer to this Root Cause Analysis for more information on this issue.
To resolve this:
- Use the taskbar search box to find "Allow an app or feature through Windows Firewall"
- Scroll down to find the "Remote Scheduled Task Management Service"
- Tick all three of the 'Domain', 'Private' and 'Public' items. The 'Domain' option will show only if your computer is a domain controller.