If I am doing a four or five shot stack I rarely get artifacts, but if the stack is in the 8-10 shot range, I find I almost always get something left over even if I do an alignment first then the stack.
This is an 8 shot stack and while it is pretty decent, way in the back trees there is some blurring effects in the trees. This is only the second in camera more than 4 shot focus stack I've tried so it may be strictly operator error. Anyone else using this feature having similar results and if so, have you overcome the issue and HOW, please.