Comment 2 for bug 1937238

This is almost certainly because you don't have the systemd-timesyncd package installed, or you don't have the systemd-timesyncd service enabled.

On a very quick glance, it seems the systemd-time-wait-sync service should have been bundled into the systemd-timesyncd package when it was split from the main systemd package, however I'll have to look closer to see if there is some reason it wasn't.