The fact that some games are fine means it isn't an installation issue for the driver so you are good there.
Some game engines are just poorly optimized for AMD cpu, gpu or both. Others for whatever reason AMD drivers need to be better optimized.
So do report your issues to AMD:
In Radeon Settings there is a Bug Report tool too you can submit the issue or
You can contact AMD support here: https://www.amd.com/en/support/contact-email-form
Also check the actual individual core utilization in the problem games. Even though the CPU may only show as half utilized, if the game mostly pushes single thread, the GPU can still be waiting on the CPU thus looking under utilized, even though the CPU isn't showing high usage.