I thought that this was settled but nope, it is not. I am doing today's lost sector. There are two barrier champions in the same room. My pulse rifle will not stun them, although the artifact says it will. Now, I never get the flash on the weapon or the text that says I can fire the weapon and stun the champion. I can hold it on them until they kill me and still nothing. The Barrier Champions are coming at me somewhat aggressively, somewhat like the Overload Champions. One came after me a minute ago and killed me. I cannot get either of their health down because if I work on one, the other one comes after me. In the meantime, the one I was shooting gets its health back. Does anyone have an idea of how to approach this?