In ArcGIS Pro I am making maps in the UK and am using British National Grid. In my layout view for the maps I have the grid lines turned on, however these grid lines are slightly skewed and do not run at right angles to each other. All my layers as well as my map space are British National Grid. I imagine this is something to do with the CS being used. Does anyone know how to make these run at right angles to each other.
I have attached an example of the maps made.