I used the straight edge to draw some charts for a puzzle game I was playing and had to figure out the offset to put the “ruler” at, because the pen draws a short distance away from the actual edge. It does this consistently.
I’m using an iPad Mini (6th gen) with an Apple Pencil (second gen) with an up-to-date version of Penbook and iOS.
@AdamNorberg I dug into this a bit and unfortunately there’s nothing we can do about it in the near term (the gap is a design choice by the underlying ink technology from Apple that we use) - sorry.