Just installed Catalyst 19.12.1 on my system with Radeon VII.
Since version 19.6.x users on Overclock.net forums were reporting that overclocking via Radeon Settings do not work for Radeon VII and its necessary to use 3rd party tools.
I tested that yesterday and can confirm the issue. Regardless Wattman settings every tool reported stock frequencies during either
Last version where everything works as expected is Radeon 19.5.2.