Lewis turned the "magic" off once he got into grid position but accidently turned in back on while shifting. I'm not a F1 programming expert, but a way to fix this is for Mercedes will add a restart that clears that toggle during the standing start. It's a simple ECU add to but in a clear rest button for standing start, it would change the selection of the switch or button and force the driver to select it through wheel. All depends if they have selection room on the wheel. Its doesn't sound like something that has happen during race until know.