I have the same problem with the auto off. I've tried the plug/unplug routine which does no good. Perhaps a new iron that is not a Rowenta? Any new suggestions on this problem?
With the setting at 4, 5, or 6 (not maximum) the iron acts as if the motion-detection is not working and goes into the auto shutoff mode even with use. The red light flashes. The only -but rather inconvenient solution - is to unplug the iron, wait a few seconds, and then plug it back in. This action apparently resets the auto shutoff, but the cycle begins a few minutes later - the red light begins flashing again and the iron starts to cool.