As bandet so astutely points out, it’s not the details of the macro that matter.
Rather, it’s a question of whether your character leaves combat in time for you to place a trap after feigning death. Usually they don’t. In my case, something changed one day such that I started leaving combat immediately — I have no idea what caused it. As I say above ‘nothing changed’ about how I was attempting to do it, it just started working all of a sudden.