So to replicate this bug you need extreme luck.
so Set the mode to Eliminate X then enable strafe.
If you are lucky enough to kill the bot where it strafed and killing the next spawning bot behind the 1st bot. the spawning bot will be invisible. It will make sound some sound cue and its harder to hit it without using a machine gun
https://www.youtube.com/watch?v=kJHzThgRMuA