Inaccuracies with pathfinder and shape builder tool
I'm using v24.3, the most recent Illustrator version. When zooming in on a shape, the selection outline does not appear to correspond to the actual fill area of the shape. When doing any cutting or merging with the pathfinder or shape builder tool, this discrepancy starts to create inaccurate results, as the tools seem to favor the selection outline as a guide when cutting.
As an example, I have a circular background. I want to "mask" a square onto it, so one of the corners of the square is outside of the circle. This corner I intend to cut off either with the pathfinder "intersect" option, or by using the shape builder tool. When I do so, however, the square seems to have an inner margin cut along the shape of the background circle, and therefore is not accurately masked.
I am including an image example. The circle only has a fill color, no stroke, and is pixel perfect.
Try to make the precision value smaller in Pathfinder Options dialog, located in Pathfinder panel’s menu. It should fix these issues.
Sorry for the late answer.