Particles initializing on the edge of the window

Hi,

I am facing an issue when I use beam "profile" = 1. The piecewise z is centered on 0. The beam always initializes at the edge of the window even when center(3) is in the middle of the box. This issue doesn't arise when beam profile = 0 is used. Please let me know if this is a bug or has an easy fix since I have tried changing center(3) but it doesn't work.

 
