Sorry for the late reply.

Copy and paste this line into your console while in SinglePlayer and check the output.
lua_run_cl print( LocalPlayer():IsSuperAdmin() )

If it says false, it's a global problem and you can't even change default settings or use Cleanup Everything, etc.

Did you ever install an admin mod (like ULX, etc.)? You should be Super-Admin by default in Sandbox SinglePlayer. If you have an admin mod, you'll need to configure it correctly or better deinstall it if you don't know how.

Could you tell me the content of the users.txt file in your garrysmod/settings folder? If it's missing, you should verify your game cache in Steam. If you haven't setup anything important there, you should delete it and then verify your game cache to get a fresh version.

Nevermind the console command "npc_antiff_rel_fear" still works.

And yes Clean up still works. I think it because I left the laptop not playing gmod for a months and most mods works broken like before restarting gmod.