There is issue where pictures are join for the background image. The join edge will always smaller than other. You can verify it by print out an inch grid line. Capture the background image using laser camera.
You will see that every join edge the line width is smaller.
How thick is your piece of wood?
I’ve found that anything with any thickness the camera capture falls apart.
It just can’t handle the parallax that occurs with objects that are raised more than a few mm off the bed.
It’s barely functional as is and if you have to re-calibrate for every piece of material it becomes completely useless and a waste of time.
There are much easier and faster ways to set your work origin.
-S