I’ve had my share of problems getting the look of engine on mobile as well and I’m no expert here. There might be a mobile specific setting somewhere in the directional light but that’s merely a guess. Would it work having two directional lights that you toggle between? At least that way the settings are in place. Maybe that’ll trick the engine into doing what you want. But I think you need to look into mobile lighting more as it’s not so straightforward it seems.