In the middle of a fight, suddenly, I couldn't use the mosue for looking up and down. If I switch to 3rd person, it still works, but NOT for my sniper rifle. My assault rifle doesn't have a scope, and it works fine with that if I look down the sights. Going into settlement building mode also eliminates the y-axis. As far as I can tell, any time the camera moves to 1st person, I lose y-axis. Anything that can be done in 3rd person works fine.

Any suggestions? I'm about 22 hours in and this just suddenly became a problem. Reloading the save didn't help. I did save afterwords like a dummy.

I found a fix for it:

Basically, just go sit in a chair and then stand back up.