WorldToScreen Interrupted While Shooting?

It seems that a simple world to screen (not using any classes for matrices) gets interrupted when any player shoots. This causes ESP Names to flicker and trying to make an aimbot that aims at the nearest player to the crosshair impossible.

Is there a solution? I couldn't seem to get CILTDrawPrim class to work as it doesn't seem I have the correct address.

Yes, you need engine address.
Simply search for DrawPrim in IDA or Olly in Engine.exe