The camera actually does see the full tray, but the software has to first de-warp the image (fisheye correction) and adjust for the height of the material. You can see an example of the raw camera image at this post:
They GFUI software crops the image so that the top-left of the displayed image is as far left and up as you can cut. It doesn’t show the top-left of the bed even though the camera can see that.
If you add an engrave operation, especially at 1000 speed, and select that operation to move it around, you will see the left-side gray bars move in.