Do you mean that he glitches out, or just that all of the taken disappear? Because if it's the latter, yes, taken champions are on a timer. You have a certain amount of time to kill the 3 lieutenants and to summon the boss and kill it. The bottom left of the screen will say "the Taken assault subsides" or something like that. It's much easier when you have help from a team or randoms who just happen to be in the area. And, 360 population seems fine to me, but If we're ever online at the same time I'll help you out. GT same as above.