Day Running Lights on car but not on caravan?

When I hitch my caravan (a 2013 Swift Challenger) onto my 2019 Land Rover Discovery 5 and connect the electrics etc, the lights on the caravan do not come on with the day running lights on the car. If I switch the car over to side or headlights (manual selection) the lights on the 'van come on. I have seen other Discovery 5's running on DRL's with the lights working on the caravan.

Could this be a wiring fault by the tow bar fitters or is there a setting on the D5 I need to implement?

Any help appreciated.