I have exactly the same problem. In various internet forums, others have also reported this behaviour. So this seems to be a common problem.

I have never experienced any problems with it. Car must be switched off. Looks like a warranty case to me....

I have also noticed that charging is much more complicated than it should be. Unfortunately it was a long time ago, but I remember that it was a certain sequence of pressing the switch and plugging it in to charge the car. maybe plugging it in and switching it on and off again or something like that, sorry I can't remember exactly. just try it out.