I must say mouse is inverted and this setting makes it proper. But nope, I just downloaded the game and the setting worked for me fine.
Yeah, it works, but it is backwards for me. I tried but I can't play with it the way it is, and the invert setting does not invert it.
I even tried restarting the game, it still won't do it.
Update: The above description was from yesterday. I started the game again today, and the invert is working now.
I don't know if shutting down Windows on my PC last night and then restarting today fixed it or if it was some other random glitch, but it is working.