Patlin
Explorer
Whether an attacker can't be seen (invisible) or isn't seen (hidden) is a distinction without a difference. You ought to be able to remain hidden for at least some time after leaving cover, and in this case it was only a round. I think the ruling was entirely correct. At most, you could have given the players a new spot check, possibly with circumstance bonuses.
A rogue ought to be able to run out of the shadows and stab someone before he is noticed, gaining a sneak attack. It might not work every time, but it should work when the apropriate skill checks are made.
A rogue ought to be able to run out of the shadows and stab someone before he is noticed, gaining a sneak attack. It might not work every time, but it should work when the apropriate skill checks are made.