What kind of controller are you using? Have you tried unplugging any second controllers you might also have plugged in?
I'm using a PS4 DualShock 4 but I also have a drawing tablet plugged in. And after unplugging it in I still had the problem and realized it was my mouse that was pulling down and after pushing up on the mouse the camera would change BUT when I let go of the mouse (and it was completely still) it would go back to revolving while looking up. Also now I have another issue where I changed some of the controls and I can't reset them to default so there are some actions like jumping, that I can't do.