Maybe you're just having picture problems. It seems there have been some problems lately. If on the place where they should be, your cursor turns into the hand, then there's something on that square even if it seems empty and you're not submiting a board with less pieces but a board where not all pieces are showing. A refresh may reveal those...
No t to mention that a 4 will loose to a mine as well... I think the only certain you have is when a 5 attacks and looses... it was definitely a mine in that case...
But I agree with Kevin: it's fine the way it is. This is a strategy and memory game after all, so "automatic revealings" would take some fun out of it...
So when it says "In standard Espionage, a player makes a move with two different pieces per turn" does it mean that the same piece can't be moved twice in the same turn?