Yes, I think I missed the point of your original question. Normally, if there was poke-through before you started the simulation, conventional wisdom would say that it wouldn't work. Conventional wisdom is sometimes wrong. :) In this case, I think the weirdness you see during the intermediate steps is the simulator sorting itself out. If the initial poke-through is too bad, it doesn't sort itself out and you get a failure. Just guesswork on my part, I haven't experimented enough to know the answer.