I just tried this and you can get it working. We are trying to have it always render the selected effect. I do notice there are a couple hiccups. You should be able to just make sure the effect is highlighted pink by clicking on it and it will actively render changes as you make them. If it doesn't seem to work try clicking to a different effect and then click back to that one. This is especially true if you hit stop while in effect rendering mode. Currently we don't do anything if you click on the effect that's already selected so clicking over to a different one and coming back fixes it.