Same in garden ops. My daughter and I had a Baron von Bats super wave the other day after rescuing a corn from the warden. BvB is now ridiculously hard to kill since the update. I kept saying to her "where the HELL is that kernel corn???" And then he'd pop in and shoot a few rounds, just to say hi I guess. At least they are good at staying alive!
But that's just annoying. Having a game mode do what flag of power did to us is way beyond lame AI teammates. The only way for me to kill the game mode was to go into an empty zombie mansion and hunt down the imp. Until I did that, the game stalled and the mode was not going to end. There were no zombies to try to wrest the flag from us. And of course, once I did kill that imp, I found myself surrounded by zombie bosses in their own turf!