Proc question on ambush

so if im assassin rogue and not in stealth and get an ambush proc in a priority rotation shouldnt i be able to list it and when it procs it goes off?

You need to understand a few things. Priority is not true priority - its mathematical probability. The true priority is you manually pressing the button to do the Ambush. A macro or a game mod cannot make that decision for you. It can only preempt and guess that maybe a proc has happened so lets try. This is all because of Blizzards Anti Botting code.