Ok, I’ve had this issue in two games now, Condemned: Criminal Origins and Dark Souls.
First, I was very surprised to see how well Condemned worked even without 3D and no changeable FOV. Just when I was ready to play a bit, at one point in the game vorpx just stops doing it’s magic. The game just goes back to the normal 2D screen layout, and the vorpx overlay and zoom don’t work anymore.
Also had this with a brief try with Dark Souls.
On a “maybe” similar note, I’ve tried Mass Effect 3 and it works really well, except when my energy shield is depleted after taking too much damage, it explodes and suddenly it’s like seperation is set to 500. completely different viewing angles for both eyes. After a while when the shield starts regenerating, it goes back to normal.