Scenario 1 is the sole where close has crossed over x, so the buy order at market will be executed immediately when bar n closes, just before bar n+1 opens (once called NEXTBAROPEN).
Scenario 2 has no condition true, since the crossing is evaluated at the closure and it did not happen at that very time. You could trigger it just changing the condition to high crosses over x, instead of close crosses over x, but still it would be triggered at the same time, not while the crossing occurs.