Well this is certainly a big red flag in my mind, and it goes right in hand with my first reply to your question...I wondered if you are actually shutting the car off or not with the switch. And it seems like you're not even sure yourself. You clearly have a bad ignition switch. This MAY be causing your problem. But since your ignition switch needs to be replaced anyway, just do it. Then see if it happens to fix your battery draw.
