tb6612fng motor driver breaks for unknown reasons

Thank you, Tom! It makes sense! Although I can't seem to recall reading about this startup/shutdown sequence in any tutorial or guide about using this chip with Arduino. Probably I didn't pay attention... So it seems I need to add an electronic switch somehow which is toggled by VCC power and supply power to VM only when it's turned on. Got any tips on how this is achieved usually? Or is it enough to just keep STBY low before powering the motors?