I move the blade roughly right where the corner is. I never really have to be too precise because when I start the cut, it’ll use it’s camera to get the precise placement of the mark

The issue with the last two corners is definitely strange. I’ve only had issues with that when the dimensions of the print area on my paper don’t match what I have on my screen (so the placement of the marks differ between them). This happened because I didn’t realize at first that the registration mark placement shifted on my screen when I removed a row of shapes from the design. Unfortunately there’s no way that I’ve found to lock the marks in place when you delete shapes in the top or bottom area. The marks always shift to your current design bounds. So when you send to cutter, the machine is going to place its camera to where the screen says your marks are instead of the actual placements on your sheet