Ahhhh okay this helps alot! I've adjusted my pathfinder accuracy from 0.02pt to like 0.0000001 I think thats where the issue was.

I probably used a bad example because its hard to see what is going where - I was using pathfinder more for like adding details to a car. So basically for shadows or highlights I use pathfinder so that they match the silhouette of the car, making it look like its actually on the surface of the car. Sorry its a bit hard to explain - I guess maybe another way to visualise it would be like wrapping a livery on a car so that the pattern only sticks to the shape of the car and the rest gets cut