Awesome, thank you. In case it helps you replicate the issue, they are 50x10mm rectangles placed at (100,100), (100,120), (100,140) etc. Latest version of Lightburn.
The problem is that 32-bit floating point math can’t perfectly represent ‘Pi’. When accounting for origin and scanning orientation, vectors are often rotated by 180 degrees, which ends up being 3.14159274 instead of 3.14159265 radians. It’s microscopic, but it makes lines angle just a tiny tiny bit, and causes a little of the shape to slip outside the bounding box for rastering. I’ve added one micron of ‘slop’ to the bounds, and that fixes it.