Mouse-look does not work, period.

[shin zaibatsu]

I can launch the game and play just fine on Plutonium, however, mouse doesn't work in menus, and mouse look does not work in game.
Yes, mouse look is on in the settings, but I cannot look around in the game. I can ADS, I can shoot, throw grenade, switch weapons, but cannot look around.
Yes, my mouse is plugged in. (Apparently some people assume that this is the problem)
I have looked for hours online, found various threads on reddit and steam, and the only mouse issues that people have involve mouse acceleration, but it doesn't affect me because I can't look around at all.

I would appreciate any and all help with my problem, thank you!