Dimensions out by 1mm

My SU drawing measures exactly, but the corresponding dimensions in LayOut are out by 1mm - even when a straight line is measured. The dimension is sometimes correct, but increases by 1mm if deleted and redone.
The LayOut has 10+ pages referencing the drawing, not every page is affected.

Is the camera angle correct?

Here’s an example, I know the square is 1m by 1m but it’s not square to the camera.

Share the LO file. I expect it’s an easy fix as Box suggests.

Not keen to share this one publicly due to confidentiality. Here it is. Let me know when you have it. https://drive.google.com/drive/folders/1uaGpYzUWD2DuiFz17SDJ7yW-Zb69COIv?usp=sharing

It is a random thing - one of two dimensions measured wrong. Move the box and the error swaps. The same drawing has correct and incorrect.

Need to have access granted. If you don’t want it made public send the link to me via a PM. I won’t share it.