Have you tried it ON when parking? Works every time like a charm for me. Come to a stop, engine shuts off, then turns back on the instant you shift to park. Annoying as all get out. Rare occurrence though, because I nearly always remember to turn ISG OFF first thing after starting up. The fact that it works for me (especially when I forget and don't want it too) is called perversity.
Mine works, but only after I've driven the car for a couple of hours. I mostly do around town driving and only drive maybe 30 miles per week on average. As a result, the battery is never fully charged. if it's not topped off, it will not meet all the conditions to allow it to turn off.
Good point about the battery. My car sat for about a week. During today's travel, this started working after about 45 minutes of driving. Time to put it on tender once in a while.
Mine hasn't worked for the past year or so, but it's 4 years old now with 70K miles and the original battery. I hooked it up to an AGM charger and the max voltage it would take is around 12.6 volts so it's showing its age. They're expensive though and the car starts strong so hopefully it makes it through the summer.