Lens shift y question

Trying to determine if there’s a bug going on with the camera.

I’m working with lens shift and I’m seeing severe inconsistencies between x and y.

With x, the shift appears to be a percentage of the image. For example, shifting 0.5 will shift the image 1/2 of the way to the left:

However, here’s what I get with a y shift of 0.5:

The entire scene has shifted off the bottom of the frame. So the ‘y’ shift control appears to be moving the camera lens much further than the equivalent ‘x’ shift (about 1.75x further by my estimate). Is this a glitch? If not I need some clarification on what the lens shift is actually telling me (when I set it to 0.5, it’s 0.5 of what?).

Never mind. Figured it out. Sorry for anybody who wasted their time reading this.