Raytracing GI settings does not affect the scene (4.27.2)

Hi. In the post-process settings, I’m switching between the “Disabled”, “Brute Force” and “Final Gather” in the Raytracing GI section, but there is no visual difference in the viewport, not even slightly. In fact, it doesn’t even have an effect on FPS.
What do you think would be a problem? Please help.

I’m using Directx12 as the default RHI. I have an RTX card, using 4.27.2. Post-process is set to unbound. Everything is set to ‘movable’.

Further investigation:
image
There is no “Enabled” checkbox as stated in the following documentation: